Trinity

Father, Son, and Holy Spirit and their relations.

Passages that substantially address this topic, in date order.

• Didache 7.1Anonymous · ca. 50–150 (often ca. 100) · Baptize in the name of the Father, Son, and Holy Spirit, in running water.
• Didache 7.3Anonymous · ca. 50–150 (often ca. 100) · If there is not enough water, pour water on the head three times.
• 1 Clement 46.6Clement of Rome · ca. 95–97 (range ca. 70–100) · One God, one Christ, one Spirit, one calling.
• 1 Clement 58.2Clement of Rome · ca. 95–97 (range ca. 70–100) · An oath by God, Christ, and the Spirit: the humble and obedient will be saved.
• To the Magnesians 13.1Ignatius of Antioch · ca. 110 (range ca. 105–135) · Stand firm in the teaching of the Lord and the apostles, with the bishop, presbyters, and deacons.
• Martyrdom of Polycarp 14.3Anonymous · ca. 156–160 · Polycarp ended his prayer with praise to God through Christ, the eternal High Priest.