The faith of the Old Testament wasn’t strictly unitarian. Ancient believers saw the one God of Israel, Yahweh, as existing in more than one “person” or hypostasis. The Old testament speaks about Yahweh, the Word of Yahweh, and the Spirit of Yahweh as three distinct divine beings.

This experience of God became clear with the Incarnation of Jesus Christ, the Son of God. At Jesus’ Baptism, the Father’s voice spoke from heaven, calling Him His Son, and the Holy Spirit appeared as a dove. God reveals himself as Trinity—Father, Son, and Holy Spirit.

This moment relates directly to what Jesus later told His disciples in the Great Commission: to baptize people “in the name of the Father, and of the Son, and of the Holy Spirit.” Christian baptism’s triple immersion “in the name of the Father, and of the Son, and of the Holy Spirit” connects us with our Lord’s Baptism in the Jordan, as every baptism is itself a glorification of God in Trinity.