虔诚（英文：Piety）用以衡量一个角色有多么虔诚敬神。虔诚会根据一系列机制自动增加。在角色去世后，虔诚会加入到分数中。
虔诚在印度教、佛教和苯教中被称作善业，在耆那教中被称作纯净，在道教中被称作德，但它们在游戏中的功能相同。
获得虔诚
- 邀请并任命一名高学识的宫廷司祭：
- 将神殿分封给廷臣可获得虔诚。（分封男爵级神殿获得25虔诚，如果神殿是伯爵领首都获得50虔诚）
- 教育两个儿童。如果你不具有愤世嫉俗特质，一些“童年个性”事件可以让你“为孩子祈祷”。（仅在御前会议DLC未激活情况下有效）
- 某些个人特质能增加每月虔诚。
狂热和
谦卑增加1 虔诚/月，
安于现状
忠贞增加0.5虔诚/月。 - 选择神学生活重心可以在隐居事件中可以获得100虔诚。
- 战争：
- 一些神殿建筑给持有者每月提供虔诚。持有者也给他们的领主提供虔诚，取决于好感。
- 一些医院建筑每月提供虔诚。
- 释放相同宗教的囚犯给予5虔诚。
- 如果囚犯持有头衔，释放他们获得虔诚（？）
- 通过向骑士团捐款，或允许廷臣（统治者的兄弟或儿子）加入他们可获得大量虔诚。
- 家族成员就任宗教领袖或骑士团团长。
Specific religions
- Christians: Go on a pilgrimage
. Catholics can also buy indulgences from the Pope. - Muslims: Sadaqah charity (not available if you're a Caliph), observe Ramadan, go on Hajj, choose humble trait in Hajj, hold mosques in your demesne, follow the
school (if Sunni), avoid the Wicked Caliph 
trait - Jews: Observe Passover.
- Pagans: Blot/Jarilo/Ukonjuhla/Uzagavenes celebration. (Not Nerge, which isn't religious.) Win county conquests and subjugation wars. Raising runestones.
- Zoroastrians: Marry close relatives.
- Dharmic religions: Go on a pilgrimage
. Diwali/Kali Puja festival. Jains receive purity (equivalent to piety) when at peace. Hindus can choose the Smartist 
branch. Non-Hindus might consider seducing into 
caste.
虔诚的作用
- 拥有大量虔诚可以让神职人员更喜欢你（每50虔诚增加1好感，在拥有500虔诚增加10好感时达到最高值）。
- 完成“成为美德典范”野心需要积累2000虔诚。
- 拥有的虔诚越多，创建或篡夺头衔时花费的财富越少（在1000虔诚时花费将减半）。
- 对于宗教领袖，虔诚可以增加宗教权威 (每点虔诚增加0.02，在在拥有1250虔诚增加25%宗教权威时达到最高值)
- 祆教徒皇帝在完全控制波斯帝国法理领地并拥有1500虔诚后可以宣布成为“救世主”。
Spending piety
- Requesting favors from your religious head costs piety:
- Request invasion
- Divorce
- Excommunication
- Lifting Excommunication
- Duchy and county claims
- Asking for money
- Some wars cost piety:
- Muslims fighting other Muslims of their faith lose 2 Piety/month.
- The Muslim-only County Conquest, Invasion and Caliphal Subjugation Casus Belli cost Piety.
- The Jain, Hindu, or Buddhist Subjugation Casus Belli costs 500 karma/purity.
- Hiring a holy order costs a lump sum of Piety. Note that Catholics can have more than 1 order, making it easier for Catholic rulers to hire holy orders.
- Creating a Kingdom costs 200 Piety.
- Creating an Empire costs 400 Piety.
- Zoroastrian emperors holding the Empire of Persia require 300 piety in order to restore the Priesthood (and create their religious head).
- The "Invite Holy Man to court" decision costs 25 Piety.
- Execution (except of heathens) reduces your Piety.
- Reforming a pagan faith costs 750 Piety.
- Muslims need 50 piety to change demesne laws and 100 piety to change crown laws.
- Muslims also need 100 Piety in order to request that a Decadent relative "straighten up".
- Secretly converting to another religion requires 250 piety; maintaining the facade during events with the liege also requires Piety.