Every character in the game follows a religion. A character's religion has a major impact on their gameplay mechanics. Cosmetically, the player character's religion determines the interface and icons used for the various alerts.
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|
|Christian||none (all Christian faiths part of core game)||Monogamy||
Variants of Christianity are uniquely peaceful toward each other, disallowing the use of religious revocation except against heretics.
|Sons of Abraham||Monogamy||
If the High Priesthood is restored, Jewish Great Holy Wars can be declared immediately. However, a unique requirement for instating the religious head is to convert the county of Jerusalem to Judaism.
|Sword of Islam||Polygamy||
Powerful Muslim CBs allow fast expansion, but large realms often fail due to dynastic decadence. All faiths of Islam (but not all heresies) can have a Caliph, a secular (and thus playable) religious head who can declare Jihads.
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.
|Pagan||The Old Gods (all Pagan faiths playable, Hellenic with limited features), Jade Dragon (only Bön playable), Holy Fury (all Pagan faiths playable, Hellenic with all features)||Concubinage (with Holy Fury varies after reformation according to faith and doctrines chosen)||
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. No religious head until reformation.
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.
With , pagan reformation adds the ability to reform with a selection of natures, doctrines, and leadership, which allows the religion to be customized to gain the benefits of other religion's abilities.
|The Old Gods (all Zoroastrian faiths/heresies playable), Jade Dragon (only Khurmazta playable)||Concubinage||
The main religion, Zoroastrianism, allows and even encourages marriages between close relatives.
If the Priesthood is restored, Zoroastrian Great Holy Wars can be declared immediately.
Heresies: All heresies are eligible for reincarnations if supernatural events are enabled.
|Eastern||Rajas of India (all Eastern faiths playable), Jade Dragon (only Taoist faith playable)||Concubinage||
Has subgroup Indian religions (Hindu, Buddhist, Jain). Characters can convert to another Indian religion if they control any province with the new religion. Provinces convert very slowly, but there is no revolt risk. No religious heads.
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||Parent religion vs its heresies, and vice versa||-25||Catholic vs a Catholic Heresy|
|Infidel||Different religion group||-20||Catholic vs Sunni|
|Zealous||Anyone of different religion||-25||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||
|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 marriage, 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 for 250 piety, Minor Holy War (vassalizes a 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
|Sects, can designate heir, Concubinage, no short reign penalty||None||Stewardship +2|
|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 Sky-Temple||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 Romuvan Congregation||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 Sacred Woods||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, reincarnation||County Conquest, Subjugation||Garrison size +40%|
|Reformed African||Pagan||The African Congregation||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 Hierocracy||Concubinage||Holy war (costs 100 piety with 5 year truce), County Conquest, Tribal Invasion, Great holy wars|
|Concubinage, Reformation, defensive attrition||County Conquest, Subjugation||
Levy size +30%
|Reformed Zunist||Pagan||The Church of Zun||Concubinage||Holy war (costs 100 piety with 5 year truce), County Conquest, Great holy wars|
|Raiding, Patron Gods, Concubinage, female temple holders, defensive attrition, reincarnation||County Conquest, Subjugation||
Garrison size +40%
|Reformed Bön||Pagan||The Sacred Bön Hierarchy|
|Unrestricted succession laws, astrology, haruspicy, female temple holders||County Conquest, Subjugation|
|Reformed Hellenic||Pagan||Collegium Pontificum|
|Concubinage, defensive attrition||County Conquest, Subjugation|
- Since 2.4.1, when a temple that is designated a holy site is destroyed, the province becomes the holy site instead, but the value of the province for moral authority is reduced by half. This was to prevent the game from crashing when nomads/tribals raze a holy site.
- Because a majority of Tengri land belong to nomads, they have no temples in most of their holy sites, forcing the player to build them.
- The Pagan religion appears for characters in the history files, representing 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, and the "Immortal Rival" event can lead to the creation of an immortal generic pagan, 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.
- The unit modifiers for reformed pagan religions apply if you do not have the Holy Fury DLC. With Holy Fury only Reformed Germanic, Reformed Tengri, and Reformed Aztec have the specified modifiers. All other reformed pagan religion no longer get any unit modifiers unless they recieve them from the selected nature or doctrines.
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 Eastern religions do not have heresies.
|Religion||Parent||Group||Head||Special Mechanics||Special CBs|
|Cathar||Catholicism||Christianity||None||Absolute Cognatic succession; female temple holders, councillors and commanders, no penalty for female rulers/heirs||Holy war|
|Fraticelli||Catholicism||Christianity||The 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; female temple holders, councillors and commanders, no penalty for female rulers/heirs, Divine marriage||Holy war|
|Bogomilist||Orthodoxy||Christianity||None||Female temple holders, no penalty for female rulers/heirs||Holy war|
|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||Autocephaly, Excommunication, Mending the Great Schism||As Orthodox|
|Zikri||Sunni||Islam||None||Decadence, Polygamy||Holy war (also vs non-Zikri, non-heretic Muslims), Muslim Invasion, County Conquest|
|Yazidi||Sunni||Islam||The Yazidi Sheikhdom (once established)||Decadence, Polygamy, Jihads, Excommunication
Yazidi has its own holy sites. They are Nishapur, Fars, Mosul, Mecca, and Jerusalem.
|Holy war (also vs non-Yazidi, non-heretic Muslims), Muslim Invasion, County Conquest|
|Kharijite||Ibadi||Islam||The Kharijite Caliphate (once established)||Decadence, Polygamy, Jihads||As Ibadi|
|Qarmatian||Shia||Islam||The Qarmatian Caliphate (once established)||Decadence, Polygamy, Jihads, Raiding. Cannot take part in the Hajj. Vassals do not mind if their levies are raised. Rulers lose prestige if at peace for too long. No Jizya tax.||Holy war (also vs non-Qarmatian, non-heretic Muslims), Muslim Invasion, County Conquest|
|Druze||Shia||Islam||None||Decadence, Polygamy, reincarnations||Holy war (also vs non-Druze, non-heretic Muslims), Muslim Invasion, County Conquest|
|Hurufi||Shia||Islam||The Hurufi Skeikhdom [sic] (once established)||Decadence, Polygamy, Jihads||Holy war (also vs non-Hurufi, non-heretic Muslims), Muslim Invasion, County Conquest|
|Mazdaki||Zoroastrian||Mazdan||None||Absolute Cognatic succession; female temple holders, commanders but NOT councillors (except the spiritual advisor), no penalty for female rulers/heirs, reincarnations. No concubines nor Divine Marriage mechanics.||Holy war|
|Manichaean||Zoroastrian||Mazdan||The Manichean Church (official title), Yamag (holding character's title).||Manichaean rulers can order courtiers to take monastic vows, like Christians, and have access to reincarnation events like Dharmics
Manichean is the only heresy with a separate Holy order.
|Holy war, Sanctioned Invasion|
|Khurmazta||Zoroastrian||Mazdan||None||Can choose a Patron Deity, reincarnations||Holy war|
|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 African||(Reformed) African||Pagan||None||Same as African||Same as 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|
|Old Bön||(Reformed) Bön||Pagan||None||Same as Bön||Same as Bön|
|Old Hellenic||(Reformed) Hellenic||Pagan||None||Same as Hellenic||Same as Hellenic|
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.
- christian: catholic; orthodox; miaphysite; nestorian;
- muslim: sunni; shiite; ibadi;
- jewish_group: jewish;
- zoroastrian_group: zoroastrian;
- indian_group: hindu; buddhist; jain; taoist
- pagan_group: norse_pagan; norse_pagan_reformed; slavic_pagan; slavic_pagan_reformed; tengri_pagan; tengri_pagan_reformed; baltic_pagan; baltic_pagan_reformed; finnish_pagan; finnish_pagan_reformed; west_african_pagan; west_african_pagan_reformed; aztec; aztec_reformed; pagan; zun_pagan; zun_pagan_reformed; bon; bon_reformed; hellenic_pagan; hellenic_pagan_reformed;
- catholic: cathar; fraticelli; waldensian; lollard;
- miaphysite: monophysite;
- nestorian: messalian;
- orthodox: bogomilist; monothelite; iconoclast; paulician
- sunni: zikri; yazidi;
- ibadi: kharijite
- shiite: druze; hurufi
- zoroastrian: mazdaki; manichean; khurmazta;
- jewish: samaritan; karaite;