From Crusader Kings II Wiki
- 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 zealots are raised and you are not fighting a holy war, dismiss them within a year to avoid piety loss.
- Large gain by giving money to holy orders, or allowing courtiers (brothers or sons of rulers) to join them.
- Granting titles to the clergy, scaled by the rank of the title
- Tutor two children. Some childhood personality events let you "pray for the child" if you are not cynical.
- Some traits award Piety per month. Zealous and Humble give 1 Piety/month, while Content and Chaste give 0.5 piety/month.
- Winning battles and occupations in wars with religious enemies grants Piety, as does winning Holy Wars and Crusades
- Some temple buildings give piety to the holder. The holder also provides piety to their liege, depending on opinion.
- Releasing prisoners gives piety if they hold titles.
- 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.
- For holy orders, you can murder a captain when you see that your kinsman has been (randomly?) selected as the heir. A kinsmen who is second or third in line will instead get a claim, which you can press (if the order is landed?).
- Christians: Go on a pilgrimage. Catholics can also buy indulgences from the Pope.
- Muslims: Sadaqah charity, observe Ramadan, go on Hajj, choose humble trait in Hajj, hold mosques in your demesne.
- Jews: Observe Passover.
- Pagans: Blot/Jarilo/Ukonjuhla/Uzagavenes celebration. (Not Nerge, which isn't religious.) Win county conquests and subjugation wars.
- Zoroastrians: Marry close relatives.
- Dharmic religions: Diwali festival. Jains receive purity (equivalent to piety) living in the peace.
Effects of piety
- Having a lot of Piety makes clergy like you more (+1 per 25 Piety, to a max of +20 at 500 piety)
- For Muslims, makes all characters of the same religion like you more
- Gaining the "Paragon of Virtue" ambition requires amassing 500 Piety.
- Creating any title costs less wealth the more pious you are (to a lower limit).
- Requesting favors from your religious head costs piety:
- Hiring a Holy Order costs a lump sum of Piety.
- Creating a Kingdom costs 200 Piety.
- Creating an Empire costs 400 Piety.
- Execution (except of heathens) reduces your Piety
- Muslims fighting other Muslims of their faith lose 2 Piety/month
- The Muslim-only County Conquest and Caliphal Subjugation Casus Belli cost Piety.
- The Jain, Hindu, or Buddhist Subjugation Casus Belli costs 500 karma/purity.