Every character in the game follows a religion. A character's religion has a major impact on their gameplay mechanics.
Interaction between religious groups is mostly limited to warfare. Characters may convert to another religion in some cases.
Six religious groups are represented in Crusader Kings II. Within each group there are variants, heresies, or both.
|Religion group||DLC required1||Marriage2||Key mechanics and variants||Common goals|
Variants of Christianity are uniquely peaceful toward each other, disallowing the use of religious revocation except against heretics.
Relations with religious head are important, as they can perform excommunication, enabling free imprisonment and a depose-ruler CB.
|Sons of Abraham||Monogamy||
|Completely control the Kingdom of Jerusalem in order to create the Kingdom of Israel and restore the high priesthood.|
|Sword of Islam||Polygyny||
Iqta government replaces both Feudal and Theocracy governments, allowing rulers to hold both castles and mosques without penalty. Iqta rulers can freely revoke duchies, and use Open succession to effectively designate heirs.
Usurp the Caliphate by claiming the existing caliph's primary title.
Or, create a new caliphate by conquering key locations and converting to a variant with no current Caliph.
|Pagan||The Old Gods||Concubinage||
Many unique mechanics make Pagans strong early on but weaker as time passes. Powerful Pagan CBs allow fast expansion, but unreformed Pagans have extreme stability problems. Can raid regardless of culture or government.
Control holy sites in order to boost moral authority and reform the religion.
Reformed religions combine the best features of paganism and existing organized religions. They consider those following the old ways to be heretics.
Tribal rulers must reform (or convert) in order to adopt feudalism or found a merchant republic.
|The Old Gods||Concubinage||
The main religion, Zoroastrianism, allows and even encourages marriages between close relatives.
Completely control the Empire of Persia in order to become Saoshyant and restore the priesthood.
|Dharman (Indian)||Rajas of India||Concubinage||
Characters can convert to another Dharmic religion if they control any province with the new religion. Provinces convert very slowly, but this is okay because there is no revolt risk. No religious heads.
Conquer the entire Indian subcontinent in order to unite India into a single de jure empire.
1Religion DLC is not required to play as a nomad; Horse Lords unlocks nomadic rulers of all religions. However, players must convert to a playable religion before they can settle down to a non-nomadic government type.
2All religions support concubinage when tribal or nomadic. For Muslims, this replaces polygamy for rulers.
|Religious Differences||Different religions of the same religious groups||-10||Catholic vs Orthodox|
|Heretic||Different religion within the same religious sub-group||-35||Catholic vs a Catholic Heresy|
|Infidel||Different religion group||-30||Catholic vs Sunni|
|Zealous||Anyone of different religion||-50||Stacks with standard penalty|
This penalty, apart from Zealous, is reduced by the Tolerance technology in the capital of each character, -6.25% per technology level. Additionally, a character who is sympathetic towards another religious group has no Infidel penalty towards or from characters following a religion of that group.
Application of Crown Laws and Offers of Vassalization
Religion affects how Crown laws are applied. This is particularly important in regions which see frequent religious conflict (Iberia, Eastern Europe and the Near East), or are simply religiously diverse (India). Independent dukes and counts are considered to have the No Crown Authority Law, if the king of the de jure kingdom which they belong to is of another religion.
AI rulers will also never accept diplomatic vassalization if they follow a different religion from the potential liege's.
Main article: Casus Belli#Religious CBs
Religion also provides various Casus Belli, most notably holy war and Crusades, though this varies from religion to religion - both are unavailable to unreformed pagans for example. Sword of Islam also introduced two new Casus Belli specifically for Muslims.
Main article: Religious head
Religion also affects what powers the religious head has; unreformed Pagan religions for example have no Religious Head, while a Christian Religious head can excommunicate characters, which is impossible for Muslims and Pagans.
Pagan religions may gain a religious head and a Great Holy War (Crusade CB) if they reform. They then become the "Reformed" version. The version without a religious head and Great Holy War becomes a heresy and is called the "Old" version of the religion.
Main article: Moral authority
Each religion has a moral authority, determined by the actions of its followers. It defines the power of the religion, and impacts the chances of heresies.
List of religions
|Religion||Group||Head||Holy Sites||Holy Sites Maps||Mechanics||Special CBs||Modifiers|
|Excommunication, College of Cardinals, Investiture, Antipope, Pilgrimage||Holy war, Crusades, Sanctioned Invasion|
|Orthodox||Christian||The Ecumenical Patriarchate||
|Autocephaly, Excommunication, Mending the Great Schism, Pilgrimage||Holy war, Sanctioned Invasion|
|Miaphysite||Christian||The Coptic Papacy||
|Autocephaly, Excommunication, Pilgrimage||Holy war, Sanctioned Invasion|
|Nestorian||Christian||The Patriarchate in the East||
|Autocephaly, Excommunication, Pilgrimage||Holy war, Sanctioned Invasion|
|Sunni||Muslim||The Sunni Caliphate||
|Decadence, Polygamy, Hajj||Holy war (also vs non-Sunni, non-heretic Muslims), Muslim Invasion, County Conquest, Jihads, Caliphal Subjugation|
|Shia||Muslim||The Shia Caliphate||
|Decadence, Polygamy, Hajj||Holy war (also vs non-Shia, non-heretic Muslims), Muslim Invasion, County Conquest, Jihads, Caliphal Subjugation|
|Ibadi||Muslim||The Ibadi Caliphate||
|Decadence, Polygamy, Hajj||Holy war (also vs non-Ibadi, non-heretic Muslims), Muslim Invasion, County Conquest, Jihads, Caliphal Subjugation|
|Judaism||Israelite||None (Kohen Gadol once the Kingdom of Israel is restored)||
|Holy war, Great holy wars, Sanctioned Invasion|
|Zoroastrian||Mazdan||None (Zoroastrian Church once the Persian Empire is retaken)||
|Divine blood, Concubinage||Holy war, Great holy wars, Sanctioned Invasion|
|Raiding, Caste System, Patron Gods, Concubinage, Sects||Holy war, Indian Subjugation||Morale +30%|
|Sects, Concubinage, can designate heir, no penalty for female rulers/heirs, no short reign penalty||Holy war (targets single county), Indian Subjugation||Learning +4|
|Sects, vassal opinion bonus, can designate heir, Concubinage, no short reign penalty||Indian Subjugation|| Demesne limit +3 |
Peace purity gain 1/month
|Raiding, river movement, Concubinage, Reformation, female temple holders, defensive attrition, 250% short reign penalty, prestige loss while at peace, no penalty from raised vassal levies||County Conquest, Subjugation, Prepared Invasion||Levy size +30%|
Retinue size +50%
|Reformed Germanic||Pagan||The Fylkirate||Raiding, river movement, Concubinage, female temple holders, 150% short reign penalty||Holy war (costs 100 piety with 5 year truce), County Conquest, Prepared invasion, Great holy wars||Levy size +30%|
|Raiding, Concubinage, Reformation, female temple holders, defensive attrition, 200% short reign penalty||County Conquest, Subjugation||Levy size +10%|
Garrison size +30%
|Reformed Slavic||Pagan||The Slavic Church||Raiding, Concubinage, Great holy wars, female temple holders||Holy war (costs 100 piety with 5 year truce), County Conquest, Great holy wars||Levy size +20%|
Garrison size +20%
|Raiding, Concubinage, Reformation, 150% short reign penalty, prestige loss while at peace, no penalty from raised vassal levies, ignores defensive attrition||County Conquest, Subjugation, Tribal Invasion||Levy size +30%|
Light Cav Offensive +30%
|Reformed Tengri||Pagan||The Tengri Church||Raiding, Concubinage, Great holy wars||Holy war (costs 100 piety with 5 year truce), County Conquest, Tribal Invasion, Great holy wars|
|Raiding, Concubinage, Reformation, female temple holders, defensive attrition, 200% short reign penalty||County Conquest, Subjugation||Levy size +10% |
Garrison size +30%
|Reformed Romuva||Pagan||The Romuva Church||Raiding, Concubinage, female temple holders||Holy war (costs 100 piety with 5 year truce), County Conquest, Great holy wars||Levy size +20%|
Garrison size +20%
|Raiding, Concubinage, Reformation, female temple holders, defensive attrition, 200% short reign penalty||County Conquest, Subjugation||Garrison size +40%|
|Reformed Suomenusko||Pagan||The Suomenusko Church||Raiding, Concubinage, female temple holders||Holy war (costs 100 piety with 5 year truce), County Conquest, Great holy wars||Levy size +10%|
Garrison size +30%
|Raiding, Concubinage, Reformation, female temple holders, defensive attrition||County Conquest, Subjugation||Garrison size +40%|
|Reformed West African||Pagan||The West African Church||Raiding, Concubinage, Great holy wars, female temple holders||Holy war (costs 100 piety with 5 year truce), County Conquest, Great holy wars|
|Concubinage, prestige loss while at peace, no penalty from raised vassal levies||County Conquest, Tribal Invasion||Levy size +30%|
|Reformed Aztec||Pagan||The Aztec Church||Concubinage||Holy war (costs 100 piety with 5 year truce), County Conquest, Tribal Invasion, Great holy wars|
|Concubinage, defensive attrition||County Conquest, Subjugation|
|Concubinage, Reformation, defensive attrition||County Conquest, Subjugation||
Levy size +30%
|Reformed Zunist||Pagan||The Church of Zun||Concubinage||County Conquest, Great holy wars|
|Pre-reformed, Concubinage, female temple holders||County Conquest, Subjugation|
- Since 2.4.1 when a barony that holds a holy site is destroyed, the province holds it instead, but the value of the province for moral authority is reduced by half. But if you build a temple in the province, it will become the holy site. This was to prevent the game from crashing when hordes raze a holy site.
- Because a majority of Tengri land belong to hordes, they have no temples in a majority of their holy sites, forcing the player to build them.
- The Hellenic and (generic) Pagan religions appear for characters in the history files, representing (for Hellenism) the pre-Christian Roman emperors and (for Paganism) pre-Christian Irish and pre-Islamic Arabs, among others. The rare "Spawn of Satan" event can lead to the creation of 3 generic pagan witches, but otherwise they cannot normally appear in-game without the console.
- Catholicism and all Catholic Heresies become Orthodox heresies if the great Schism is mended. This does not affect the Miaphysite or Nestorian denominations.
All religions with a parent religion are heresies. With Sons of Abraham, if a heresy becomes more prevalent than the parent religion (5 provinces more), it will become the new orthodoxy, and the parent religion will become a heresy. All holy orders of the parent religion switch over to the former heresy when this happens. Note that the Indian religions do not have heresies.
|Cathar||Catholicism||Christianity||None||Absolute Cognatic succession; female temple holders, councillors and commanders, no penalty for female rulers/heirs|
|Fraticelli||Catholicism||Christianity||Fraticelli Pope (once established)||Excommunication, College of Cardinals, Investiture, Antipope, Crusades||As Catholic|
|Monophysite||Miaphysite||Christianity||The Monophysite Papacy||Autocephaly, Excommunication||As Orthodox|
|Messalian||Nestorian||Christianity||None||Absolute Cognatic succession; Divine blood, female temple holders, female councillors and commanders, no penalty for female rulers/heirs|
|Bogomilist||Orthodoxy||Christianity||None||Female temple holders, no penalty for female rulers/heirs|
|Monothelite||Orthodoxy||Christianity||The Monothelite Partriarchate||Autocephaly, Excommunication, Mending the Great Schism||As Orthodox|
|Iconoclast||Orthodoxy||Christianity||The Iconoclast Patriachate (once established)||Autocephaly, Excommunication, Mending the Great Schism||As Orthodox|
|Paulician||Orthodoxy||Christianity||The Paulician Patriarchate (once established)||Autocephaly, Excommunication, Mending the Great Schism||As Orthodox|
|Zikri||Sunni||Islam||None||Decadence, Polygamy||Muslim Invasion, County Conquest|
|Yazidi||Sunni||Islam||The Yazidi Sheikhdom (once established)||Decadence, Polygamy, Excommunication
Yazidi has its own holy sites. They are Nishapur, Fars, Mosul, Mecca, and Jerusalem.
|Muslim Invasion, County Conquest|
|Kharijite||Ibadi||Islam||The Kharijite Caliphate (once established)||Decadence, Polygamy||As Ibadi|
|Druze||Shia||Islam||None||Decadence, Polygamy||Muslim Invasion, County Conquest|
|Hurufi||Shia||Islam||The Hurufi Skeikhdom [sic] (once established)||Decadence, Polygamy||Muslim Invasion, County Conquest|
|Mazdaki||Zoroastrian||Mazdan||None||Can borrow money from Jewish Merchants|
|Old Germanic||(Reformed) Germanic||Pagan||None||Same as Germanic||Same as Germanic|
|Old Slavic||(Reformed) Slavic||Pagan||None||Same as Slavic||Same as Slavic|
|Old Tengri||(Reformed) Tengri||Pagan||None||Same as Tengri||Same as Tengri|
|Old Romuva||(Reformed) Romuva||Pagan||None||Same as Romuva||Same as Romuva|
|Old Suomenusko||(Reformed) Suomenusko||Pagan||None||Same as Suomenusko||Same as Suomenusko|
|Old West African||(Reformed) West African||Pagan||None||Same as West African||Same as West African|
|Old Aztec||(Reformed) Aztec||Pagan||None||Same as Aztec||Same as Aztec|
|Old Zunist||(Reformed) Zunist||Pagan||None||Same as Zunist||Same as Zunist|
When a pagan religion is reformed, anyone following it gets an event to decide whether to accept the reformation. If they don't, they become the "Old" version, which is considered a heresy. The reformed version keeps the name of the pre-reformation religion.
Likewise, if an Orthodox ruler mends the Great Schism, Catholic rulers get an event to decide whether to convert to Orthodoxy (or the "heresy"). Either way, Catholicism is thereafter treated as an Orthodox heresy, and all the Catholic heresies become Orthodox heresies instead. Orthodox Heresies can also mend the Great Schism if they manage to replace Orthodoxy as the parent religion.
catholic; orthodox; sunni; shiite; miaphysite; jewish; cathar; bogomilist; zikri; bektashi; monophysite; mazdaki; fraticelli; nestorian; yazidi; druze; manichean; waldensian; monothelite; ibadi; hurufi; zoroastrian; lollard; iconoclast
pagan; hellenic_pagan; norse_pagan; norse_pagan_reformed; tengri_pagan; tengri_pagan_reformed; baltic_pagan; baltic_pagan_reformed; finnish_pagan; finnish_pagan_reformed; aztec; aztec_reformed; slavic_pagan; slavic_pagan_reformed; west_african_pagan; west_african_pagan_reformed; zun_pagan; zun_pagan_reformed