Excommunication is an act of censure by a religious head. The church officially cuts all ties with the character, causing major diplomatic issues. It is available for most branches of Christianity, and for the Yazidi heresy of Sunni Islam.
Requesting an Excommunication
Any ruler can ask for another ruler of the same religious denomination to be excommunicated if:
- The requester pays the cost of 100 piety, or 50 piety with Papal Investiture.
- The religious head dislikes the target and likes the requester. Vassal religious heads will also always grant the excommunication requests of their lieges.
- The target does not control the religious head. This typically means that the Byzantine Emperor can never be excommunicated.
- The target does not control more cardinals than the requester (for Catholics, with Sons of Abraham DLC).
- The target did not recently have an excommunication lifted.
A few event chains can also lead to excommunication.
Being excommunicated will:
- bomb opinion: -5 diplomacy and an additional -30 opinion from characters of the same religion. For rulers, this makes it considerably more difficult to manage a realm, and makes faction rebellion more likely.
- give every ruler in the same ecclesiastical branch an excommunication Casus Belli which they can use upon the excommunicated ruler, and if successful will reverse the excommunication, at the cost of a large amount of prestige, and force the ruler to abdicate.
- if vassal, liege may imprison excommunicated vassals without incurring tyranny, making this a potent tool to deal with a troublesome vassal. Excommunicated characters who are imprisoned can also be executed without penalty.
Excommunication will end:
- automatically upon the death of the excommunicated character or the religious head
- if using the (very expensive) "Make Declaration of Repentance" decision. You can ask him to lift the excommunication directly for 100 piety (50 with Papal investiture) if he likes you enough.
- if establishing an antipope, which ends excommunication as realm no longer obeys the Pope.
Keep your religious head's opinion of you positive, especially if you know another ruler would like to see you excommunicated
- Bribe your religious head. If Catholic, bribe a newly elected Pope, before gifts become too expensive.
- Send your Chancellor to Improve Diplomatic Relations (less effective in Constantinople, where you have a 50% chance of pleasing the Basileus instead)
- Excommunicate vassals for free imprisonment and/or execution
- Excommunicate rivals to soften up their realms before attacking.
- Depose excommunicated rulers to make their child heir inherit. This makes the realm more vulnerable to weak claims.
- Reinstate deposed rulers - newly abdicated rulers gain a strong claim on their old realm. If you grant them a landed title, you can push their claim and thus expand.
- Excommunicate your heir for free imprisonment, and subsequently order them to take the vows to get rotten heirs out of the way of your strong genius younger son.
- Send your Court Chaplain to Improve Religious Relations with your religious head.
- Go on a pilgrimage
- Charity decision
- Go on hajj
- Join a jihad