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：
- Some temple buildings give monthly piety to the holder. The holder also provides piety to their liege, depending on opinion.
- Some hospital buildings give monthly piety
- Releasing prisoners of your religion gives 5 piety.
- Releasing prisoners gives piety if they hold titles (?)
- Large gain by giving money to holy orders, or allowing courtiers (brothers or sons of rulers) to join them.
- Install dynasty members as religious heads or holy order captains.
- Gives all same-religion rulers of your dynasty (of count rank and higher) +1 monthly piety and +2 monthly prestige.
- For the Papacy, see controlling the College of Cardinals.
- Holy orders use Open Elective succession, which is based on the sum of age and prestige. See Advanced marriage guide for strategies to increase dynasty prestige. You can murder the captain and others in line for the title, or press claims against a landed holy order.
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.