Module 03: The Trinity: Father, Son, and Holy Spirit

The doctrine of the Trinity became formally orthodox through the councils of Nicaea in 325 and Constantinople in 381. However, not all Christians accept this doctrine. Those who reject the Trinity do not all reject it for the same reason. Some reject the Trinity because they believe Jesus is not God, but is instead the Messiah, Son of God, and Spirit-filled representative of God.

The doctrine of the Trinity is one of the most debated teachings in Christianity. Trinitarian Christians usually believe it because they think it best explains the full pattern of Scripture, worship, salvation, and Christianity. The strongest argument for the Trinity is based on several claims that Trinitarians believe must be held together.

One of the debates in the early Christian Church was how Christians could worship the God of Israel, give divine status to Jesus, and describe the Holy Spirit as divine, without breaking monotheism. The doctrine of the Trinity is the most common way Christians answer this question.

The doctrine of the Trinity became central to Christianity because early Christians were trying to explain how they could continue to believe in one God while also giving divine status to Jesus Christ and the Holy Spirit.

Module 3 explains the doctrine of the Trinity as the mainstream Christian attempt to hold together three claims at once: there is one God, Jesus is treated in divine ways, and the Holy Spirit is understood as divine and active. It traces how this doctrine developed historically through early Christian debates and church councils, then explains the core Trinitarian claim that God is one in essence and three in persons: Father, Son, and Holy Spirit. The module also presents the main biblical, historical, logical, relational, and salvation-based arguments that Trinitarians use to defend this doctrine.