The Trinity – One God in Three Persons | She's a Theologian: Learning to Know God as Christian Women

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    The Trinity is a foundational doctrine of the Christian faith. Scripture teaches that God is one in essence and eternally exists in three Persons: the Father, the Son, and the Holy Spirit. This truth defines how Christians understand God and how they worship Him.

    The Bible alone is the source of this doctrine. The Old Testament affirms that the Lord is one (Deut 6:4). The New Testament presents the full divinity of the Father (Jn 6:27), the Son (Jn 1:1; 20:28), and the Holy Spirit (Acts 5:3–4). These three are not interchangeable or symbolic. Each Person is distinct and fully divine (Matt 3:16–17). This is not also polytheism. Scripture affirms that there is only one God who eternally exists in three co-equal and co-eternal Persons.

    The Trinity appears across the whole of Scripture. In Matthew 28:19, Jesus instructs His disciples to baptize “in the name of the Father and of the Son and of the Holy Spirit.” The phrase uses a singular “name” while naming three Persons. In 2 Corinthians 13:14, Paul describes the Christian life through the work of all three: “The grace of the Lord Jesus Christ, the love of God, and the communion of the Holy Spirit.”

    Throughout church history, major errors have arisen when this doctrine is altered. Modalism presents God as one Person who takes on different roles or forms. This view collapses the distinctions seen clearly at Jesus’ baptism, where the Son is baptized, the Spirit descends, and the Father speaks (Matt 3:16–17). Others reject the full divinity of the Son or the Spirit. This contradicts Jesus’ own words in John 10:30 and the apostolic witness to the divine knowledge and power of the Spirit (1 Cor 2:10–11).

    The Trinity also explains how God acts in salvation. The Father planned redemption (Eph 1:4–6). The Son accomplished it (Eph 1:7). The Spirit applies it and seals those who believe (Eph 1:13). Each Person is involved from beginning to end. This doctrine helps us understand how we are saved and how we live in fellowship with God.

    Scripture does not provide a full explanation of how this mystery works. It provides the truth we are to confess. Christians are called to receive what God has revealed and worship Him as He is. The Trinity cannot be explained through comparison or reduced to earthly images. It must be believed because it is true.