The Great Schism refers to the formal split between the Eastern (Orthodox) and Western (Catholic) branches of Christianity.

The split was the result of centuries of growing political, cultural, and theological divergence.

Key theological disputes included the 'filioque' clause, which the West added to the Nicene Creed, and the nature of papal authority.

The Pope in Rome claimed universal jurisdiction over the entire church, a claim rejected by the Patriarch of Constantinople.

Cultural and linguistic differences (Latin West vs. Greek East) exacerbated the tensions.

The immediate crisis of 1054 involved a dispute between Pope Leo IX and Patriarch Michael Cerularius.

The papal legate, Cardinal Humbert, excommunicated the Patriarch in Constantinople.

In response, the Patriarch excommunicated the papal legate.

While 1054 is the traditional date, the schism was a long process, not a single event.

The sack of Constantinople by Western crusaders in 1204 solidified the split and created lasting animosity.