James the Just

Paul calls him 'the Lord's brother' (Galatians 1:19) — Catholic and Orthodox tradition read that as kinsman or step-brother through Joseph's prior marriage; Protestants read it as literal sibling. He ran the Jerusalem church for thirty years. He's the one who chaired the Council of Jerusalem in Acts 15, the meeting that decided Gentile converts didn't have to keep the Mosaic Law — the single most consequential decision in early Christian history. Without that ruling, Christianity stays a Jewish sect. His letter is the most practical book in the New Testament: religion is feeding widows, controlling your tongue, not flattering rich people. Josephus records that he was killed by the high priest in AD 62, which Jewish writers themselves later said helped doom Jerusalem.