在游戏的宗教系统中
虔诚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，在耆那教中被称作德，但它们在游戏中的功能相同。
Gaining Piety
- Invite and appoint a lord spiritual with high learning skill:
- You get a small monthly piety gain based on state learning, increased by Majesty technology
- If tribal, having your lord spiritual Build Zeal gives +0.05 piety per skill per month. With 20 learning this comes out to +1 piety/month.
- If zealot troops are raised and you are not fighting a holy war, dismiss them within a year to avoid piety loss.
- Granting a temple to a courtier gives piety (25 piety if barony tier, 50 piety if county capital)
- Tutor two children. Some childhood personality events let you "pray for the child" if you are not cynical. (Only without Conclave)
- Some personality traits award Piety per month.
and 
give 1 Piety/month, while 
and 
give 0.5 piety/month. - Theology Focus can give 100 piety in seclusion event.
- Warfare:
- Winning battles and occupations in wars with religious enemies grants Piety
- Winning holy wars gives you an opportunity to grant temples for 25 Piety each, or even entire counties for more Piety
- Contributing to successful Holy Wars and Crusades grants Piety
- 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.
Effects of piety
- Having a lot of Piety makes clergy like you more (+1 per 50 Piety, to a max of +10 at 500 piety)
- Fulfilling the "Paragon of Virtue" ambition requires amassing 500 Piety.
- Creating or usurping titles costs less wealth the more pious you are (down to 1/2 price at 1000 piety)
- For religious heads, increases moral authority (+0.02%/point, maximum +25% MA with 1250 piety)
- Zoroastrian emperors who completely control the Empire of Persia and have accumulated 1500 piety can declare themselves the Saoshyant.
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.