Is Trinitarianism biblical? What exactly is Trinitarianism?

from the old testament

• Deuteronomy 6:4 says, “The LORD our God, the LORD is one,” clearly affirming that God is one. That statement emphasizes monotheism, not numerical simplicity. The Hebrew word for “one” (echad) can refer to a unified whole, such as one cluster of grapes or one flesh in marriage, allowing for complexity within unity.
• As early as Genesis 1 we begin to see hints of plurality within the Godhead. In Genesis 1:26, God says, “Let us make man in our image, after our likeness,” and then follows it with, “So God created man in his own image, in the image of God he created him; male and female he created them” (Genesis 1:27). This pattern of a plural pronoun followed by a singular one also appears in Genesis 3:22, 11:7, and Isaiah 6:8. While some explain these as examples of royal language, the surrounding context consistently limits the reference to God alone. These passages likely give early glimpses of the triune nature of God, even if the full doctrine of the Trinity had not yet been revealed.
• In addition to the pronoun hints, we see two other Persons clearly mentioned within the Old Testament who also appear to be God: the Spirit and the Angel of the LORD.
• The Spirit of God is described as present and active from the opening lines of Scripture (Genesis 1:2; Psalm 104:30). He is later seen speaking and acting with divine authority (2 Samuel 23:2–3; Ezekiel 2:2). In these cases, the Spirit is both personal and divine—pointing to His identity as the third Person of the Trinity.
• The Angel of the LORD also appears throughout the Old Testament as a distinct Person who speaks as God, receives worship, and yet is not the Father. In Genesis 22, for example, it is God who commands Abraham to sacrifice Isaac (Genesis 22:1–2), but when the Angel of the LORD stops Abraham, He says, “Do not lay your hand on the boy or do anything to him, for now I know that you fear God, seeing you have not withheld your son, your only son, from me” (Genesis 22:12). God gave Abraham the command, yet the Angel of the LORD said that Abraham had obeyed Him. Thus, He is somehow distinct from God yet also identified as God. Most scholars believe that the Angel of the LORD is a preincarnate appearance of the Son, later known as Jesus.
• Isaiah 48:16 provides a rare passage where all three Persons seem to be present: “Draw near to me, hear this: from the beginning I have not spoken in secret, from the time it came to be I have been there.” And then it continues, “And now the Lord GOD has sent me, and his Spirit.” The One speaking is Yahweh, who says He was sent by Yahweh along with His Spirit. Though subtle, this passage strongly anticipates the clearer Trinitarian language of the New Testament.
• These examples are not conclusive by themselves, but they point toward a triune understanding of God that the New Testament makes explicit. The idea that God is one in essence and three in Person is, therefore, not a theological invention. Rather, it’s an idea embedded in the very fabric of the Old Testament.

from the new testament

• The full clarity of the Trinity is revealed in the New Testament. At Jesus’ baptism, all three Persons are present: the Son is baptized, the Spirit descends like a dove, and the Father speaks from heaven, affirming His pleasure in the Son (Matthew 3:16–17). This scene shows that God is not one Person revealing Himself in different forms, but three Persons acting at the same time.
• Jesus teaches the doctrine directly in the Great Commission, commanding His followers to baptize “in the name of the Father and the Son and the Holy Spirit” (Matthew 28:19). The use of the singular word “name” followed by three Persons underscores both unity and distinction within the Godhead.
• For His part, Jesus is explicitly called God. For example, John opens by saying, “In the beginning was the Word, and the Word was with God, and the Word was God” (John 1:1; c.f., John 20:28). He also claims divine authority, forgives sin, receives worship, and shares in the Father’s glory (John 5:23; 14:9; Matthew 14:33). In John 8:58, He uses the divine name “I AM” for Himself, which provokes an immediate attempt to stone Him (John 8:59; c.f. Exodus 3”14). These claims only make sense if Jesus truly is God in the flesh.
• At the same time, Jesus operates in submission to the Father. He said, “I have come down from heaven, not to do my own will but the will of him who sent me” (John 6:38). His mission was unique: to live a sinless life and die as a substitute for sinners (Philippians 2:8; John 19:30). As the eternal Son, He shares the divine essence; as the incarnate Messiah, He fulfills a distinct role in the plan of redemption.
• The Holy Spirit is also revealed as a divine Person. He teaches, guides, speaks, and can be grieved (John 14:16–17; Acts 13:2; Ephesians 4:30). In Acts 5:3–4, lying to the Spirit is equated with lying to God. The Spirit, then, is not an impersonal force. Rather, He is God, having the distinct role of dwelling with and in believers all the while pointing them to Jesus.
• Though distinct Persons, because they are of the same divine essence, they always work together in perfect unity. For example, passages like 2 Corinthians 13:14 and Ephesians 1:3–14 include all three Persons working together in salvation. The Father chooses (Ephesians 1:4), the Son redeems (Ephesians 1:7), and the Spirit seals (Ephesians 1:13). Each Person is fully God, fully personal, and fully involved.
• The New Testament never tries to explain how this mystery “works.” Instead, it simply reveals it as true. God is one in essence, three in Person—Father, Son, and Holy Spirit—eternal, coequal, and united in all they do.

implications for today

The Trinity is not an abstract nor made up theological formula—it is the very nature of God as described in Scripture. Indeed, if God were not triune, salvation itself would fall apart. Only the Father could send the Son. Only the Son could take on flesh, live without sin, and bear the wrath of God in our place. Only the Spirit could open our hearts, apply redemption, and unite us to Christ.

Rejecting the doctrine of the Trinity is to reject the true God of the Bible. There are many religions which claim to be Christian, but then deny Jesus’ divinity, reduce the Spirit to a force, or even believe that God changes expressions to sometimes be the Father, sometimes the Son, and sometimes the Spirit. These are fatal misunderstandings of who God is, and why the church has historically condemned them as heretical. Any other version of God than the One revealed in the Bible cannot save.

But if you have trusted in the triune God, then you have trusted in the true God! You can rest in the work of the Father’s plan, the Son’s sacrifice, and the Spirit’s presence. Your salvation is secure because the triune God has accomplished it.

Take this time to worship Him for who He is. Part of being God means that we can’t fully understand Him. The Trinity is something we can’t understand. Allow that to humble you and to cause you to look up at Him in awe!