Why wasn’t the Trinity revealed in the Old Testament?

Although there are a number of tantalizing hints of God’s triune nature in the Old Testament,

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the full doctrine cannot be understood without the light of the New Testament. This fact can lead to a question, or even an objection:

“If God is triune, why is this not revealed in the Old Testament? Shouldn’t something that important have been something that Abraham and Moses would have known about?”

One response, which certainly has its place, is that the foundation of monotheism needed to be firmly in place before the concept of the Trinity could be properly understood. The Old Testament itself bears consistent witness that God’s people were constantly falling away from singular devotion to Yahweh in order to worship the gods of the peoples around them. If a prophet in this context had begun talking about the deity of Father, Son and Holy Spirit, this surely would have been interpreted as three separate gods, the beginnings of a Hebrew pantheon. (And once you’ve got three, why not go on and throw in Baal and Chemosh and Molech…) Once Israel had finally come to understand, once and for all, that the God who brought them out of Egypt is the only god, only then was it possible to reveal that this one God exists in three persons.

Another response to the question, which gets at something even more fundamental, comes from the pen of B.B. Warfield:

The real reason for the delay in the revelation of the Trinity, however, is grounded in the secular

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development of the redemptive purpose of God: the times were not ripe for the revelation of the Trinity in the unity of the Godhead until the fulness of the time had come for God to send forth His Son unto redemption, and His Spirit unto sanctification. The revelation in word must needs wait upon the revelation in fact, to which it brings its necessary explanation, no doubt, but from which also it derives its own entire significance and value. The revelation of a Trinity in the Divine unity as a mere abstract truth without relation to manifested fact, and without significance to the development of the kingdom of God, would have been foreign to the whole method of the Divine procedure as it lies exposed to us in the pages of Scripture.

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What Warfield is saying is that the progressive unfolding of God’s revelation is tightly coupled to the progressive unfolding of his plan of salvation. The primary purpose of God’s word is not to fill our heads with interesting theological facts, but to help his people understand the meaning of his activity in history as he works out his plan of redemption. For this reason, God’s word hasn’t come in a steady stream down through the centuries, but in batches clustered around major events in salvation history, such as the Exodus and the life of Christ. In fact, Warfield argues that the revelation of the Trinity isn’t in the New Testament either, but in the historical events which the New Testament is the fruit of:

We cannot speak of the doctrine of the Trinity, therefore, if we study exactness of speech, as revealed in the NT, any more than we can speak of it as revealed in the OT. The OT was written before its revelation; the NT after it. The revelation itself was made not in word but in deed. It was made in the incarnation of God the Son, and the outpouring of God the Holy Spirit.

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This explains why the authors of the New Testament never sit down to explain the Trinity per se, but simply take it for granted as the common possession of the Church, speaking naturally as trinitarians talking to other trinitarians.

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In the end, there’s nothing surprising about when and how the Trinity appears in the Bible. The mistake we make is in assuming that the Bible is supposed to be a Systematic Theology textbook, when what we find instead is an organic record and explanation of God’s dealings with his people.

The secret thing belong to the Lord our God, but the things that are revealed belong to us and to our children forever.
Deuteronomy 29.29

1. See for example Genesis 1:26-27, Proverbs 30:4, Isaiah 9:6, Daniel 7:13-14, 27.

2. “Existing or continuing through ages or centuries”, secular, definition 3.b, https://www.merriam-webster.com/dictionary/secular

3. Warfield, Benjamin B. “Trinity.” Edited by James Orr, John L. Nuelsen, Edgar Y. Mullins, and Morris O. Evans. The International Standard Bible Encyclopaedia. Chicago: The Howard-Severance Company, 1915. https://www.internationalstandardbible.com/T/trinity-1.html

4. Ibid.

5. I mentioned a couple examples from 1 Peter in a previous article.