In Crusader Kings 3’s By God Alone, the Great Schism is a progress bar in the Christian Church Situation that fills as the Roman and Greek Rites clash; once it reaches its threshold, the Saeculum Obscurum Chapter unlocks the Cause the Great Schism and Prevent the Great Schism decisions. If neither side acts before that Chapter ends, the Schism happens automatically, and after it you can only reunite the Church through a Mend the Great Schism decision.
This is a paid feature of Crusader Kings III: By God Alone, and it only plays out in full from the 867 start, where East and West still share one faith. Below we explain what fills the bar, how to cause or prevent the split, and how to mend it. Details come from Paradox’s launch changelog and its seventh dev diary; for everything else in the expansion, see our By God Alone feature guide.
How the Great Schism Works
At the 867 start, Catholic and Orthodox Christianity do not exist yet. Everyone follows Chalcedonianism, split into Rites: the Roman Rite in the West, and the Greek, Slavic and Georgian Rites in the East. Chalcedonianism has no Head of Faith, so Rome and Constantinople are only Heads of Rite.
The Schism is not one of the Situation’s seven Chapters. Paradox describes it as a second track on the same Situation window, a bar that keeps updating whatever Chapter the Church is in. Per the changelog, progress never decreases. Christian players get a notification each time it grows.
In the 1066 and 1178 starts, the Schism has already happened, so the Cause and Prevent decisions are disabled. Only mending remains.
What Pushes the Schism Forward
Paradox’s changelog and dev diary list these sources of schism progress:
- A king of one Rite declaring war on a king of the other.
- A king or landed prelate switching between the Roman and Greek Rites (this can also fire The One Left Behind event).
- A Holy Site converting between the two sides, or being demoted.
- Excommunications across the Rites, or a Head of Rite murdered or anathematized by the other side.
- Ecumenical Councils, which Paradox calls a major source of progress. Before debates open, the Rites can quarrel over First Among Equals, the Bread of the Altar or the Matter of Language. Defusing the quarrel adds no progress; taking a side or overruling a Rite does.
When the bar hits its threshold, The Wound Will Open event warns you that the next Saeculum Obscurum Chapter is where the Schism will be decided.
How to Cause or Prevent the Great Schism
Once the threshold is reached and the Church enters Saeculum Obscurum, three options open:
- Cause the Great Schism breaks communion and triggers the split.
- Prevent the Great Schism keeps Christendom together and fires Communion Preserved for every Christian ruler. The peacemaker may then seat a spiritual Head of Faith at Rome or Constantinople, or refuse and leave the Church without one.
- Sway Schism Stance is an interaction that urges another ruler to take your side. Paradox’s dev diary says acceptance depends on whether you ask them to betray their own Rite, whether they are a religious head, their Personal Tenets, and whether they are Zealous or Cynical.
Per the dev diary, both decisions need a king or above who is Head of Faith, a Head of Rite, or who has one of those offices as a clerical Puppet. The checklist also asks for very high Piety, control of the necessary Holy Sites, and the backing of seven clerical Main Power rulers who share your stance and are already your Puppet, friend, lover, or under your Hook. Check the decision tooltip in your game for the exact list, since the diary predates launch.
If no one finishes either decision before Saeculum Obscurum ends, the Schism happens on its own. The effect is the same either way: Catholicism takes the Western Rites and the Papacy, Orthodoxy takes the Eastern Rites and the Ecumenical Patriarchate, and Chalcedonianism is gone for good. Characters who picked a stance convert with their Rite. Afterwards, Catholics and Orthodox treat each other as Astray rather than Hostile.
How to Mend the Great Schism
Once the split has happened, Chalcedonianism cannot come back. Instead, one side absorbs the other’s Rites. Paradox’s dev diary describes two decisions:
- Mend the Great Schism Through Conquest asks an emperor to hold the five old Patriarchal Sees with same-faith bishops.
- Mend the Great Schism Through Diplomacy asks a king to Hook, befriend or Puppet both Heads of Faith and gather clerical support on both sides.
The dev diary ties mending to the Concord Chapter, and the Concord description says Christian kings or emperors may try to mend the Schism there. The launch changelog lists the diplomatic version alongside the Saeculum Obscurum decisions, so check which Chapter your game requires in the decision tooltip. A character who caused the Schism cannot mend it.
The payoff is large: per the changelog, mending gives the mender’s dynasty 10,000 Renown and a permanent modifier.
Tips for Steering the Schism
- Use the Guide the Christian Church decision (once every ten years) to push the Situation toward the Chapter you need. Taken as Head of Faith, it has four times the effect.
- If you want Rome’s side to win the vote over time, the Papacy matters: our guide on how to become Pope covers the College of Cardinals.
- A Puppet counts. You do not need to hold a religious office yourself if you control someone who does.
- Watch your wars. Every king-on-king war across the Rites feeds the bar, and it never goes back down.
For the wider launch picture, including the free update, see our By God Alone launch news.
Frequently Asked Questions
Can you stop the Great Schism in Crusader Kings 3? Yes, in an 867 game with By God Alone. Take the Prevent the Great Schism decision during Saeculum Obscurum once the progress threshold is reached.
Why can’t I cause or prevent the Schism in 1066? By 1066 the Schism has already happened, so those decisions are disabled. Only the Mend decisions are available.
Does schism progress ever go down? No. Paradox’s changelog says progress never decreases.
What happens if nobody decides? The Schism happens automatically when the Saeculum Obscurum Chapter ends.
Is the Great Schism in the free 1.20 update? No. It is part of the paid By God Alone expansion.