What is the biggest difference between Orthodox and Protestant Christians?

Eastern Orthodox and Protestant Christians share the ancient core of the faith: the Trinity, Jesus as fully God and fully human, his death and resurrection. Like Catholics, Orthodox Christians hold Scripture together with sacred Tradition and the early church councils as authoritative, while most Protestants hold Scripture alone as the final authority.

Orthodoxy's own emphasis differs somewhat from Catholicism's, too. Orthodox Christians don't recognize the Pope's authority, don't hold a formal doctrine of purgatory, and place special weight on icons, ancient liturgy, and something called theosis—the idea that Christians are gradually transformed to actually share in God's own life, not just declared forgiven.

Protestants tend to emphasize a decisive moment of personal faith and Scripture's authority above any human institution. Orthodoxy emphasizes unbroken continuity with the ancient church through unchanged worship and teaching.

Both traditions affirm the historic Christian creeds and treat Jesus's death and resurrection as central to salvation.