Part 16

Manage Heresy: Heresy is the worst religion, capable of appearing anywhere and converting your populace. While low-piety heretics are usually easy to remove by killing their religious agents and then using your own priest/imam to reconvert the area, avoid intentionally inviting heresy. Heretics can sometimes help Catholic priests gain piety.

Convert Other Religions: If you plan to conquer settlements or have significant populations of other religions, send priests/imams to convert them to your official religion to simplify governance.

Understand Crusades (Catholic): To initiate a Crusade, Catholic factions must ask the Pope. This typically requires a relationship of 5+ crosses with the Pope. Factions excommunicated cannot start or join Crusades, but can be targeted by them. Armies on Crusade move farther per turn, have 0 upkeep, and can recruit special religious mercenaries. Participating factions gain experience and money, and generals gain loyalty, chivalry, and command traits. Crusades can only be called against specific settlements, often including Capitals and rebel settlements.

Understand Jihads (Islamic): Any Imam with 5+ piety can call a Jihad. Unlike Crusades, Jihads are less complicated but less effective due to fewer Islamic factions. Similar to Crusades, armies on Jihad have benefits like increased movement, 0 upkeep, and access to special religious mercenaries. Factions gain experience and money, and generals gain traits. Jihads can only be called against specific settlements. Orthodox factions do not have a religious war option.

Joining Holy Wars: To join a Crusade or Jihad, build an army with at least one family member and 8 units. Then, on the family member's information scroll, find and press the "Join Crusade/Jihad" button.

The Papal States: The Papal States, starting with Rome, cannot be destroyed but can be stripped of settlements. Attacking them will result in excommunication, so it's best done in the later game. If Rome is taken, the Pope moves to another region and may return after his death, but will not retake Rome without force or concession. The Pope is the Faction Leader, and the three most pious Cardinals from separate factions can become Preferati, automatically assuming the role of Pope upon the previous one's death.