Early Christianity, the period of Christianity preceding the First Council of Nicaea in 325 AD. This typically divides historically into the Apostolic Age and the Ante-Nicene Period (from the Apostolic Age until Nicea). The first Christians, as described in the first chapters of the Book of Acts, were all Jews either by birth or conversion and historians refer to them as Jewish Christians. The early Gospel message spread orally, probably originally in Aramaic, and later in Greek. The New Testament's Acts of the Apostles and Epistle to the Galatians record that the first Christian community centered on Jerusalem and that its leaders included Peter, James, the brother of Jesus, and John the Apostle.