We’re taking a look at one of the core doctrines of the Christian faith: belief in God as Trinity. We believe in one God who eternally exists as Father, Son, and Holy Spirit. As classical theologians have sought to explain it, God is “one Being, three Persons.”
In Part One, I pointed out that belief in the Trinity was not a post-biblical doctrine that was introduced into the church through later pagan corruption. Rather, it was a conviction Christians held from the very start. Detailed definitions of Trinitarian theology gradually became more developed as these early believers sought to make better sense of how they had experienced the very presence and power of God himself in the person of Jesus of Nazareth and through the Holy Spirit in their midst, and as they sought to defend this view of God against later heresies.
In light of that, we should ask: How does Scripture speak of God in a way that reveals we should think of him as a Trinity? That’s what we’ll be exploring today.
Where Is the Trinity Revealed In Scripture?
In answering this question, it’s important to keep in mind the manner in which God has revealed himself throughout history.
God didn’t drop a finished book from heaven containing everything there is to know about him. Rather, he revealed himself bit-by-bit over time, letting his people gradually get to know him better as they witnessed his faithfulness down through the centuries.
This is called progressive revelation — it was a process; it didn’t happen overnight.
That’s why we don’t see too much information about the Trinity spelled out in the Old Testament. In that era, it was enough progress for God to get his people to reject all false gods and trust in him alone.
This is why the Old Testament puts so much stress on God’s oneness.
Trinity in the Old Testament?: Hints and Foundations
The central creed of Israelite faith was this: “Hear, Israel: Yahweh is our God. Yahweh is one” (Deuteronomy 6:4, WEB).
In a world filled with rampant polytheism, God took pains to stress his uniqueness as the one and only Most High God, the “God of gods” (Psalm 50:1, Hebrew).
In Isaiah 42:8 we’re told that the one true God will not give his glory to anyone else, nor share his praise with false gods. One God; not many gods. (The New Testament also stresses God’s oneness: Romans 3:30; Galatians 3:20).
(Now, spoiler alert!: Keep in mind this idea that God won’t share his glory with anyone else — it’ll be important when we see how the New Testament talks about Jesus!)
But that doesn’t mean the Old Testament rules out God’s three-in-oneness!
In multiple places throughout the Hebrew Scriptures, God addresses himself in a way that suggests the different members of the Trinity are speaking to one another:
“Your throne, God, is forever and ever; the scepter of your kingdom is a scepter of justice. You love righteousness and hate wickedness; therefore God, your God, has anointed you with the oil of joy more than your companions.” — Psalm 45:6-7 (CSB, underlining added)
“This is the declaration of the Lord to my Lord: ‘Sit at my right hand until I make your enemies your footstool.'” — Psalm 110:1 (CSB)
“Then he showed me the high priest Joshua standing before the angel of the Lord, with Satan standing at his right side to accuse him. The Lord said to Satan: ‘The Lord rebuke you, Satan! May the Lord who has chosen Jerusalem rebuke you!'” — Zechariah 3:1-2 (CBS)
Those first two passages from the Psalms are later picked up in the New Testament, where they are applied to Jesus as the divine Son of God being exalted by the Father (see Mark 12:35-37; Hebrews 1:3-13).
The third passage involves an important Old Testament figure — the “angel of the Lord.” This heavenly emissary appears frequently throughout the OT, and although God has many other ordinary angels in his service, there’s a special uniqueness to “the angel of the Lord.” Whenever he shows up, he is treated as a manifestation of the presence of God (see Genesis 16:7-13; Exodus 3; Judges 6:11-24; 13:2-23; Zechariah 12:8). Many passages make it clear that those who see the angel of the Lord have seen the Lord himself.
For example, look at Judges 13:20-22:
“When the flame went up from the altar to the sky, the angel of the Lord went up in its flame. When Manoah and his wife saw this, they fell facedown on the ground. The angel of the Lord did not appear again to Manoah and his wife. Then Manoah realized that it was the angel of the Lord. ‘We’re certainly going to die,’ he said to his wife, ‘because we have seen God!'” (CSB, underlining added)
And yet, in other passages (like Zechariah 3:1-2 which we quoted above), the angel of the Lord is also somehow distinct from the Lord, and speaks of the Lord in the third-person.
Because the angel of the Lord somehow is God and yet is also distinct from God, numerous interpreters throughout history have understood him to be the pre-incarnate Christ — God the Son appearing in visible form to act as the Father’s agent on earth.
All of these Old Testament passages contain only subtle hints of God’s nature as Trinity. That reality becomes clearer in the New Testament, when God the Son steps into human history as Jesus of Nazareth. With the foundation of God’s oneness having been firmly laid, it was time for his three-in-oneness to be more fully revealed.
We’ll take a close look at what the New Testament reveals about the Trinity in the next post.
 I can’t resist adding a little technical note here: The Hebrew word used in Deut. 6:4 to describe God as “one” is the word echad. It’s helpful to note that this word is also used in Gen. 2:24 to describe how a husband and wife join together to become “one flesh” (basar echad). Thus, echad can describe a kind of oneness that involves composite unity (such as the composite unity of a Trinity!).
 Another possible place where we may see a hint of the Trinity is right at the beginning of Scripture, in Genesis 1:26, where God says, “Let us make man in our image, according to our likeness” (CSB). Many Christian commentators throughout history have seen this as a hint of the Trinity, but this is highly debated. This verse is more likely depicting God making a pronouncement to his angelic divine council, which is a common motif in ancient Near Eastern creation stories. Therefore, it probably shouldn’t be the first verse you turn to to find the Trinity in the Old Testament. Although, that said, we do see God the Father and God the Spirit both acting in this passage, in Genesis 1:1-2. For more info, see the NET Bible note on Genesis 1:26.