Religion

For information on individual religions, see religions and denominations.

Religion interface

The religion that a nation follows and how tolerant it is of other faiths is an important aspect of gameplay in EUIV. The religion of a nation will confer specific benefits, enable different mechanics, and affect diplomatic actions as nations of mutually accepted religions have a better chance of reaching agreements with one another. Religion is also connected to unrest and provinces of non-tolerated religions are more rebellious. The player has some control over religion by having the option to change the state religion, send missionaries to convert heathen or heretic provinces to the state religion, and carry out religious decisions.

Religion map

Religion by province in 1444. For a legend, see Religions and denominations.

Religious unity

Religious unity is the percentage of a country's development provided by provinces that follow the state religion or a positively tolerated heretic or heathen religion, excluding any assigned to trade companies.

• Provinces of the state religion always contribute 100% unity regardless of tolerance.
• Provinces of a heretic or heathen religion contribute a percentage determined by how tolerated they are.

The effects of tolerance on religious unity per province are as follows:

Tolerance	Contribution
Negative Tolerance	+0%
0	+25%
1	+50%
2	+75%
3	+100%

For example, suppose a Catholic country has a 10 development Catholic province, a 4 development Protestant province, and a 16 development Sunni province. If heretic tolerance is +1 and heathen tolerance is -2, the country's religious unity will be (100% * 10 + 50% * 4 + 0% * 16) / (10 + 4 + 16) = 40%

Ideas and policies which increase religious unity:

	Traditions	Ideas	Bonuses	Policies
+50%	—	Bengali idea 1: Bengali Hindu-Sufi Syncretism Gujarat Sultanate idea 1: Garba! Indian Sultanate idea 1: Tolerate the Idol Worshipers Jaunpuri idea 3: Sants and Sufis	—	—
+33%	South Indian traditions	—	—	—
+30%	Sami traditions	—	—	—
+25%	Bosnian traditions Granadan traditions Papal traditions Punjabi traditions	Humanist idea 1: Tolerance Bahmani idea 2: Legacy of Gisu Daraz Hessian idea 3: Welcome the Reformers Kazani idea 1: Steppe Tolerance Malvi idea 2: Malvi Art & Architecture Permian idea 6: Komi Tolerance Zaporozhian idea 6: Steppe Tolerance	—	—
+20%	American traditions Ayutthayan traditions	East Frisian idea 3: Center of Religious Thought Javan idea 1: Candi Shrines Karamanid idea 6: Home of the Whirling Dervishes Burmese idea 3: Nat Worship West African idea 4: Ancestors and Crescent	—	Defensive-Religious: Edict of Expulsion Humanist-Aristocratic: Enlightened Aristocracy Religious-Diplomatic: Policy of Calculated Delay Religious-Offensive: The Anti-Heresy Act
+15%	—	Smolenskian idea 1: Smolenskian Resolve	—	—
+10%	—	Ansbach idea 4: Franconian Reformers Gond idea 2: Tribal Religion Highlander idea 4: Episcopalianism Pueblo idea 6: Clown Societies	—	Exploration-Religious: Colonial Restrictions

Religious unity directly affects the following:

• for each percentage point of religious unity:

	+0.01	Monthly fervor
	+0.05	Maximum absolutism

• for each percentage point of religious unity below 100%:

	+1.0%	Stability cost modifier
	+0.03	National unrest
	−1.0%	Church power
	−0.01	Yearly devotion
	+0.001	Yearly Corruption

Tolerance

Countries have three tolerance values. These tolerance values are national, but have provincial effects depending on the province's religion, relative to the state religion.

Each point of positive tolerance gives:

−1

Local unrest

Each point of negative tolerance gives:

	+1.25	Local unrest
	−10%	Local tax modifier
	−10%	Local goods produced modifier

Additionally, positive tolerance of heretics and heathens allows those provinces to contribute to religious unity (see above).

Note that Hungary and the United States have national ideas which remove all penalties for having negative tolerance.

Tolerance of the true faith

This refers to the state religion. For example, if the state religion is Catholic, Catholic provinces will use this tolerance value. The base value of tolerance of the true faith is +3, and there is no maximum value.

Ideas and policies that affect tolerance of the true faith:

	Traditions	Ideas	Bonuses	Policies
+3	Byzantine traditions	—	—	—
+2	Ladakh traditions Lan Xang traditions Laotian traditions Leonese traditions Québécois traditions Romanian traditions Sukhothai traditions Tapuian traditions Tirhuti traditions	Religious idea 4: Devoutness Ainu idea 6: Yukar Al-Haasa idea 2: Lord of the Bedouin of the East Amago idea 6: Kizuki Antemoro idea 5: Religious Control Ardabili idea 3: Leader of all Shiites Asakura idea 6: Control of Buddhist Sects Asturian idea 2: Camino de Santiago Bharathi idea 5: Ganga Bremish idea 2: Memories of Verden Cham idea 1: Memory of the My Son Temples Chernihiv idea 6: Renovate the Transfiguration Cathedral Chosokabe idea 7: Support of the Temples Cornish idea 3: Prayer Book Traditionalism Danish idea 7: Religious Freedom is Atheism Dithmarscher idea 2: Kirchspiele Farsi idea 1: Land of the Persians French ducal idea 4: Religious Conviction Fulani Jihad idea 5: Islamic Scholarship Garhwali idea 6: Protecting the Land of the Gods Garjati idea 6: Jagganath Cult Georgian idea 3: Legacy of Saint Nino Greek idea 1: Greek Orthodox Faith Hejazi idea 1: Custodian of the Two Holy Cities Interlacustrine idea 4: Holy Lineages Khorasani idea 6: Great Sheiks of Khorasan Kitabatake idea 2: Blessing of Amaterasu Lan Na idea 4: The White Elephant Lorraine idea 6: Trois-Évêchés Manipur idea 4: Mayek Medri Bahri idea 2: Christian Legacy Miao idea 1: Sacrificing to the Spirits Moravian idea 2: Religious Sanctuary Mossi idea 6: Honoring the Masks Münster idea 1: Great Procession Najdi idea 7: Enforce Tawhid Northumbrian idea 3: Cradle of British Christianity Offaly idea 4: The Fear of God Ogasawara idea 7: Zenko-ji Orleanaise idea 5: The Cathedral of Orleans Papal idea 1: Ecclesiastical Primacy Pegu idea 3: Dhammazedi Pueblo idea 6: Clown Societies Rajputana idea 5: Protectors of the Dharma Rostov idea 3: Ecclesiastical Center Sami idea 5: Defend the Noaidi Traditions Samtskhe idea 7: A Sacred Land Songhai idea 6: Sharia Tokugawa idea 6: Toshogu Transylvanian idea 6: Unitarian Zeal Tumbuka idea 4: Office of the Mulwa Tyrconnell idea 3: Religious Patrons Württemberger idea 5: Grosse Kirchenordnung Yarkandi idea 4: Empower the Khojas Yi idea 5: Promote the Bimoism	Mushasha ambition	—
+1	Clanricarde traditions Thomondian traditions	Croatian idea 4: Antemurale Christianitatis Dhundhari idea 3: Restore Hindu Ceremonies Gujarati Princedom idea 5: Protect the Dwarkadhish Temple Hatakeyama idea 3: Mount Koya Kanem Bornuan idea 4: House of Kanem Khmer idea 2: Theravada Buddhism Kievan idea 5: Center Of Orthodox Church Montenegrin idea 2: Metropolitanate of Montenegro Muscovite idea 3: Seat of Metropolitan Bishop Nepalese Princedom idea 3: Institute New Festivals Ruthenian idea 7: Birth of Russian Orthodoxy Sindhi idea 4: Expand the Makli Ncropolis Swahili idea 3: Great Mosque of Kilwa Teutonic idea 7: One State, One Religion Theodorian idea 7: Cave Monasteries Tunisian idea 7: Tunisian Caliphate Utrecht idea 1: Devotio Moderna Vindhyan idea 3: A Sacred Land Welsh idea 7: Welsh Church	—	—

Additional modifiers:

• +0.5 for ‘Trading in’ incense
• –2 for ruler with ‘Sinner’ personality

Tolerance of heretics

This refers to different religions within the same religious group. For example, if the state religion is Catholic, the religion group is Christian, and provinces that are Protestant, Reformed, Coptic, Orthodox, or Anglican will use this tolerance value. The base value of tolerance of heretics is −2. The possible maximum value is +3.

Ideas and policies that affect tolerance of heretics:

	Traditions	Ideas	Bonuses	Policies
+4	Athenian traditions Bosnian traditions Cypriot traditions Naxian traditions	—	—	—
+3	Dali traditions Lithuanian traditions	Ajami idea 2: In Honor of Ali Bohemian idea 1: Compacta of Prague Dutch idea 5: Embrace Humanism Qara Qoyunlu 3: In Honor of Ali Saxon idea 4: Wittenberg University Transylvanian idea 5: Patent of Toleration	Polish ambition	—
+2	Al-Haasa traditions	Humanist idea 3: Ecumenism Baden idea 4: Cuius Regio, Eius Religio Burgundian idea 6: Allow Freedom of Worship Canadian idea 5: The Quebec Act East Frisian idea 5: Refuge of the Mennonites French idea 7: Liberté, Égalité, Fraternité Ilkhanid idea 2: Favor Sufism Kurdish idea 2: Li Gora Gawirî Kurd Misilman e Lur idea 4: Popular Religion Pomeranian idea 4: Religious Freedom Ruthenian idea 2: Foreign Influences Swiss idea 5: Swiss Tolerance Thüringian idea 3: Protector of Reformers Utsunomiya idea 7: Mount Nikko	Gelre ambition	Religious-Plutocratic: The Tolerance Act
+1	—	Albanian idea 6: Albanian Tolerance Arawak idea 4: Tribal Tolerance Circassian idea 7: Religious Flexibility Frisian idea 6: Difference of Opinion Garhwali idea 7: Crossroads of Faith Kikuchi idea 5: Religious Coexistence Ouchi idea 6: Welcome the Westerners Prussian idea 7: Religious Toleration Sligonian idea 7: Pragmatism Over All Tibetan idea 4: The Way of Virtue Vijayanagar idea 4: Tolerance	—	—

Heretic conversion events

Tolerance of heretics of ≥ 2 will allow provinces to randomly convert to those heretic religions. The mean time to happen is 5000 months, lowered by Innovative Ideas and having a neighboring province with the new religion while increased by having the Theocracy government type. Provinces with the "Religious Zeal" modifier will not receive these events at all.

A province is more likely to convert via event to a particular religion if a neighboring province has that religion. Adjacency is not required for most conversions. However, the following conversions only occur if a neighboring province has the new religion:

• Orthodox ↔ other Christian
• Buddhist, Shinto → Confucian

In addition, only Japanese-culture provinces can convert to Shinto as the result of a event.

Tolerance of heathens

This refers to religions of other religious groups. For example, if the state religion group is Christian, provinces that are of Muslim, Eastern, or Pagan religious groups will use this tolerance value. The base value of tolerance of heathens is −3. The possible maximum value is +3.

Ideas and policies that affect Tolerance of heathens:

	Traditions	Ideas	Bonuses	Policies
+3	Ottoman traditions Semien traditions	Andalusian idea 3: Alh Ulh Dhimma Granada idea 1: People of the Book Rûmi idea 4: Sultan of Rûm Siddi idea 1: Goma	—	—
+2	Javan traditions Kaffan traditions Kazani traditions Malian traditions Pagarruyung traditions Permian traditions	Humanist idea 7: Humanist Tolerance Arakanese idea 2: Rohingya Immigrants Carib idea 6: Religious Syncretism French idea 7: Liberté, Égalité, Fraternité Golden Horde idea 7: Religious Pragmatism Guarani idea 4: Jesuit Conversions Ito idea 6: Sympathy for New Faiths Kutai idea 2: Muslim Trading Communities Laotian idea 3: Satsana Phi Luzon idea 4: Tagalog Syncretism Malayan sultanate idea 2: Sufi Legacy Mindanao idea 1: An Islamicized Barangay Mysorean idea 3: Religious Tolerance Omani idea 3: Association With Unbelievers Sadiyan idea 2: Crossroad of Religions Tripuran idea 3: Religious Syncretism	Samtskhe ambition	—
+1	Jerusalem traditions	Albanian idea 6: Albanian Tolerance Circassian idea 7: Religious Flexibility Frisian idea 6: Difference of Opinion Garhwali idea 7: Crossroads of Faith Kikuchi idea 5: Religious Coexistence Ouchi idea 6: Welcome the Westerners Sligonian idea 7: Pragmatism Over All Tibetan idea 4: The Way of Virtue Vijayanagar idea 4: Tolerance	—	Humanist-Exploration: Native Assimilation Act

Defender of the Faith

Each Christian or Muslim denomination can have one Defender of the Faith. It costs 500 ducats for a country to claim the title. Countries with female rulers or regencies cannot claim the title. Being Defender of the Faith gives the following modifiers:

	+5%	Morale of armies
	+5%	Morale of navies
	+5%	Technology cost
	−0.025	Monthly war exhaustion
	+1	Yearly papal influence
	+1	Yearly prestige
	+1	Missionary
	+0.5	Yearly devotion

Additionally, all other countries of the same religion get a +10 “Defender of Faith” relations boost with the title holder.

Countries automatically call the Defender of the Faith of their religion to arms if attacked by a nation of another religion. Since patch 1.8, it seems the Defender of the Faith gets a call to arms only for countries on the same continent or sharing their border. The Defender of the Faith doesn't get a call to arms if the country attacked is a co-belligerent (e.g., if France is the Catholic Defender of the Faith and Venice (Catholic) is allied with Serbia (Orthodox), then if Ottomans (Sunni) attack Serbia and make Venice co-belligerent, France doesn't get a call to arms).

Catholic countries that hold the Defender of the Faith title cannot be excommunicated by the Papacy, regardless of relations.

The Defender of the Faith loses the title, but no prestige, if they refuse or lose the war.

If Defender of the Faith refuses a call to war, it gets a 5-years truce with the country that was calling. Therefore, if your ally is Defender of the Faith and you have a common enemy of the "defended" religion, this ally will not be able to join you in an offensive war against this enemy, as AI wouldn't break a truce.

Note: If the title holder ends any war with a result other than a white peace or victory, the title will be lost.

Conversion

Province conversion

The most common way to convert provinces is the use of missionaries, but there are also several other methods. If you have the Cradle of Civilization DLC , you have the ability to directly convert your subjects' provinces to your subjects' State religion.

Missionaries

Missionaries are envoys that can convert a province to a nation's official religion. Missionaries slowly convert provinces over time: each month, the effective missionary strength in that province is added as ongoing progress, and when it reaches 100% the province is converted. If strength is insufficient (less than 0%), the province will never convert (although the missionary will not lose progress). An active missionary in a province will increase the unrest there by +6%.

Each country has 1 missionary by default. More can be obtained through the following:

Conditions

+1

Defender of the faith. Coptic holding Alexandria (358) Hindu holding Varanasi (2095) Inti (reformed) holding Lima (809) Mahayana holding Luoyang (1836) Mayan (reformed) holding Sotuta (846) Nahuatl (reformed) holding Cholula (2644) Orthodox holding Alexandria (358), Antioch (2313), Constantinople (151), Jerusalem (379) and Roma (118) (as long as all provinces are Orthodox) Sikh holding Doaba (2075) as long as the province is Sikh Theravada holding Kandy (2099) Vajrayana holding Lhasa (677) Buddhist holding Patna (558) Christian holding Mecca (385) Muslim holding Mecca (385) and Medina (384) Christian (non-Catholic) or Muslim holding Roma (118) Christian, Jewish or Muslim holding Jerusalem (379) “Propagation of State Religion” as active issue. as Shinto with Isolationism as Feudal Theocracy

Ideas and policies:

	Traditions	Ideas	Bonuses	Policies
+1	Asturian traditions Divine traditions Sindhi traditions Castilian traditions	Religious idea 1: Missionary Schools Ajuuraan idea 3: Gareen Imams Circassian idea 4: Franciscan Missionaries Ethiopian idea 5: The Ark of the Covenant Fulani Jihad idea 1: Wandering Scholars Jerusalem idea 4: Land of the Heathen Münster idea 3: Founding of Monasteries Mushasha idea 2: Messianic Legacy of Muhammad bin Falah Najdi idea 2: Hanbali School Otomo idea 5: Christian Converts Teutonic idea 6: Promote Prussian Bishops Tyrconnell idea 4: St Patrick's Purgatory Utrecht idea 5: City of Churches	Bremish ambition Leinster ambition Munster ambition Najdi ambition Northumbrian ambition	—

Decisions and events:

	Event modifier	Trigger	Duration
+2	Counter-Reformation	Decision: “Embrace the Counter-Reformation”	until one of the four “The Counter-Reformation Ends” events.
+1	Melchior Klesl	Austrian event: “Melchior Klesl” Option: ‘Such devotion! We have need of this man on the privy council.’	until ruler changes.

Missionary maintenance

The player can adjust the missionary maintenance cost by a slider on the economy interface between zero and full funding. Reducing the funding reduces missionary strength linearly, up to −5% missionary strength without funding. At full funding the costs of an active missionary per month is calculated based on the development and local autonomy of the province as follows:

${\text{Monthly cost}}={\frac {8.3\times {\text{province development}}^{\left(1+{\text{autonomy}}\right)}}{100}}$

The following ideas reduce missionary maintenance cost:

	Traditions	Ideas	Bonuses	Policies
−50%	—	Religious idea 6: Inquisition	—	—

Missionary strength

Base missionary strength is 2%. Modifiers that increase strength include:

• Advisors: +2% from an Inquisitor advisor
• Stability: +0.5% for each point of positive stability
• Piety: Up to +3% for Muslim states that are inclined towards Mysticism
• Patriarch Authority: Up to +2% for Orthodox states that have Patriarch Authority.
• Coptic Blessing: +1.5% for Coptic states that have the Send Monks to Establish Monasteries blessing. ( Rights of Man only)
• Building: +3% for a Cathedral
• Decisions: A number of national decisions increase (or decrease) missionary strength.
• Events: Many events give a temporary bonus (or penalty) to missionary strength.
• Province's current religion: +2% in pagan provinces.
• Holy Roman Empire: +1% for being the dominant religion in the Holy Roman Empire
• Estate: +2% in provinces controlled by the clergy estate if clergy loyalty is above 60%.
• Converting religions through the Religion tab gives a +10% "Religious Zeal" bonus for ten years, but only to converting heretics, not heathens.
• Several ideas also affect missionary strength:

	Traditions	Ideas	Bonuses	Policies
+3.0%	—	Religious idea 3: Divine Supremacy Byzantine idea 7: Restore the Ecumenical Patriarch	—	—
+2.0%	Bremish traditions Jerusalem traditions Najdi traditions	Asturian idea 5: Millenarian Revival Armenian idea 1: Apostolic Church Austrian idea 5: Edict of Restitution Castilian idea 2: Spanish Inquisition Divine idea 4: Let No Man Tolerate the Witch Hindustani idea 6: Patronize Sufi Missionaries Javan idea 3: Dharmasastra Kanem Bornuan idea 4: House of Kanem Moldavian idea 5: Metropolis of Moldavia Nubian idea 5: Nubian Religious Unity Pagarruyung idea 1: Tantric Legacy Palatinate idea 5: Heidelberg Catechism Rigan idea 4: Denounce Withcraft Savoyard idea 4: Crush the Vaudois Sindhi idea 2: Bab ul Islam Sumatran idea 2: Porch of Mecca Teutonic idea 4: Assume Religious Authority Utrecht idea 5: City of Churches	Tsutsui ambition	—
+1.0%	Ajuuraan traditions Lan Xang traditions Tibetan traditions	Air idea 7: Ineslemen Teachings Arabian idea 4: Spreading the Prophet's Word Athenian idea 6: Preserve Archbishop of Athens Breton idea 4: Breton Catholicism Fulani Jihad idea 3: Fulani Jihads German idea 5: Cuius Regio, Eius Religio Hejazi idea 6: Hajj Khivan idea 4: Djuma Mosque Kievan idea 5: Center Of Orthodox Church Leinster idea 1: Legacy of Palladius Muscovite idea 3: Seat of Metropolitan Bishop Novgorod idea 2: City of Churches Québécois idea 7: Jesuit Missions Sukhothai idea 4: Wat Si Sawai	Sami ambition	Religious-Aristocratic: The Witchcraft Act Religious-Diplomatic: Policy of Calculated Delay Religious-Espionage: Enforce Religious Law Religious-Trade: Religiously Sponsored Guilds

In addition, a few ideas specifically affect missionary strength when converting heretics, but have no effect when converting heathens.

	Traditions	Ideas	Bonuses	Policies
+3%	—	Bavarian idea 4: Establish the Geistlicher Rat Rûmi idea 7: Protector of Dar al-Islam	—	Religious-Offensive: The Anti-Heresy Act
+2%	—	Aachen idea 5: Expel Heretical Officials Ardabili idea 4: Conversion of the Masses Bulgarian idea 2: Root Out the Heresies Flemish idea 3: Beeldenstorm Irish idea 4: Loyal Catholics Manx idea 6: Burn the Heretic Mushasha idea 7: Sufis and Shias of the Middle East Ulster idea 5: Catholic Ascendency	Finnish ambition Münster ambition	—
+1%	Kievan traditions	Clevian idea 3: Avid Reformers Welsh idea 7: Welsh Church	—	—

Things that decrease this speed include:

• Province's current religion: −2% in Coptic, Muslim and Shinto provinces.
• Province's current religion: −1% in Orthodox and Sikh provinces.
• Culture: −2% for non-accepted cultures.
• Trade company provinces get −100%
• Provincial development: −0.1% for each point of a province development level.
• Religious Centers: Rome, Mecca, the initial Sikh province and all Protestant and Reformed Centers of Reformation get −5%.
• Recently converted provinces get −100%, called Religious Zeal for 30 years.

Centers of reformation

The first three European nations to convert to Protestant, the first three to convert to Reformed, and a British nation if it takes one of the appropriate choices to convert to Anglicanism, have a random European province designated as a Center of Reformation. These centers of reformation will automatically convert nearby provinces to their religion. Provinces converted by a center of reformation get the −100% religious zeal modifier to missionary strength in that province for 30 years. Missionaries can't work in the same province that is being converted by a center of reformation. Each center of reformation can only convert one province at a time. Players will receive a notification if all provinces within the center's range have been converted to its religion.

A center of reformation is destroyed if its province is converted to another religion. The primary method for a Catholic nation to slow or stop the spread of the reformation is to conquer and convert a province with a center of reformation, thereby eliminating its missionary effect on neighboring provinces.

A center of reformation will cease to convert provinces after start of the Age of Absolutism.

Conversion using trade policy

Muslim nations can enable "Propagate religion" policy in trade nodes inside a trade company region, provided that they control at least 50% of trade power in this node. While this policy is active, it will work the same way as a center of reformation.

National conversion

There are several different ways a country may change religion.

By direct action

Some religions may convert among certain heresies/sects via the Religion panel, at a cost of 100 prestige. This is true for Catholic, Protestant and Reformed Christians, Hindus and Sikhs once Sikhism is unlocked, as well as all Buddhists. Conversion by this method will give a whopping 10% missionary strength against heretics for ten years, making conversion of provinces of the old faith quite rapid, unless it is entirely blocked due to local Religious Zeal modifiers. Sikhs can also convert to Sunni or Shia Islam this way.

Conversion is also possible through decisions in some cases, which causes a -4 stability hit (except for Sikh or Sunni/Shia conversion, which only reduces it by 2). With the Sword and Crescent DLC, Sunni and Shiite (but not Ibadi) Muslims may convert to the other denomination if both their capital and the majority of their province development follows the other denomination. Japanese daimyos, but not the Shogun or Japan itself, may convert to Catholicism by decision if the majority of their territories are Catholic, which can happen following certain events in the 16th century. Pagan nations that are not Tengri may convert to any non-Pagan faith if they control a province of that faith; Tengri nations are limited to Vajrayana Buddhism. Muslims owning a Sikh province may also decide to convert to Sikhism - this decision probably mostly exists to allow Punjab to easily follow its historical religion.

By event

Totemist and Animist pagans get events to convert to Catholic, Protestant, or Reformed Christianity if they have neighbors of the appropriate denomination and a sufficient positive opinion with that neighbor. Tengri pagans with a dominant secondary faith may be prompted to change to it or face a -3 stability hit; they also have event chains that end in conversion to their secondary religion.

Kongo and Ming have special event chains to convert to Catholicism.

A nation in the British region, typically England, can get an event, based on the wives of Henry VIII, to convert to Anglicanism with the Rule Britannia DLC.

Some nations, for example Sweden, have unique events enabling them to change religion.

Countries that have the Indian Sultanate government by default, but are neither Muslim nor were forcefully converted to another religion, will quickly be forced to choose by event between conversion to the appropriate branch of Islam, or facing a large amount of rebels and a stability hit. This generally only is the case if they have been released as a vassal or in a peace deal, which will likely make them Hindu initially, because Indian sultanates rarely convert the local religion, and indeed have no need to due to their large bonus to heathen tolerance. AI will always choose to convert.

Forced conversion by other nations

A nation can force a heretic country to change their state religion as part of a peace deal. The revolutionary target may also do this to heathens. Without an appropriate casus belli such as "Cleansing of Heresy" or "Religious Conformance" (unique to the Holy Roman Emperor against HRE members), this will have the same war score cost as annexing the nation. When a country is converted this way, only the state religion and the capital province's religion change.

Once the religion of the Holy Roman Empire has been locked, the emperor can also request a prince to change their state religion depending on their opinion of the Emperor. Similarly to when forcing a religion of an enemy country, the prince has its capital converted while the rest of the provinces remained unaffected.

With the Common Sense DLC, suzerains may force their subject nations to change religions if they follow a different faith. If heretic, this gives +50 liberty desire, and if heathen +100 liberty desire, both gradually ticking down.

Forced conversion by rebels

Nations can support religious zealots in other countries. These rebels convert a province's religion to the one they represent when occupation is achieved.

Supporting religious zealots is only possible if the desired religion is present in the target nation and is the likely rebel type in a province with unrest above 0. If there are no such provinces in the target nation, one way to achieve it is to sell the target a province of the correct religion.

Generally the nation will be able to overpower the rebels if left to its own devices, so it is critical to support them militarily. This can be done by declaring war against the target nation using the "Support Rebels" casus belli.

A nation that is broken by religious rebels, or that accepts their demands, will convert to the rebels' religion provided that the rebels' religion is the plurality religion in terms of development. For most countries, giving in to religious rebels is the only way to change between religious groups.

However, only Animist rebels, not other types, can convert a non-Pagan nation to a Pagan faith. Thus Animism must serve as a springboard to conversion to other pagan faiths.

Strategy

• Base missionary strength is very small compared to modifiers, both positive and negative. This means that conversion can be very fast or impossible. Religious ideas are sometimes essential to make any progress conversion work.
• Provinces that do not have the state religion generally suffer from low tolerance and also lower the nation's Religious Unity. With that, nations that are challenged with large numbers of wrong-religion provinces will have to choose between dealing or not dealing with them, and with the 1.26 update the main way of dealing with them as a large nation is to be highly tolerant (usually by using the Humanist idea group).
• Several Triggers for Religions give bonuses or penalties. You should keep in mind these Triggers to optimize your religious conversion. See Triggered modifiers

Achievements

Defender of the Faith

Become Defender of the Faith.

Footnotes

Province mechanics