As folks on this side of Revelation, it’s sometimes difficult to figure out what to do with some of the Old Testament. Doctrines which seem so well developed in the New Testament seem to be shadowy at best in the Old. Sometimes we get lost in the form (which is still important) of the Old Testament and miss the substance; at other times we look for things in the substance of the Old Testament which we see so clearly in the new and find only crickets.
The doctrine of the Trinity is probably a good example of this. Some folks look into the Old Testament and find no evidence for it, and others (like some of the Church Fathers) look into the Old Testament and find it everywhere. Some totally discount any notions of plurality in God as revealed in the Old Testament, and others look at the thrice-holy cry of the heavenly court in Isaiah 6 and see the Triune God clearly revealed there.
Perhaps, when we think of the Trinity in the Old Testament, we should take a more measured approach. On the one hand, the Triune God is the Triune God regardless of whether we’re speaking of time as it was before Christ’s Advent or after. On the other, though, we shouldn’t expect all the facts which we know about God to be revealed in the Old Testament for a number of reasons. Geerhardus Vos, the man who some have called the father of the biblical theology movement, is a helpful corrective to the temptation to the extreme on either side. He gives three reasons why we shouldn’t look for a decisive proof of the Trinity in the Old Testament.
Old Testament revelation was not finished but only preparatory. Vos isn’t saying here that the Old Testament is wrong by any means, but only incomplete. The Old Testament is meant to be paired with the New, and thus trying to find a decisive proof for the Trinity would be sort of like looking for the surprise ending at the beginning of the book. There might be shades of it there, but it’s primarily preparing you for the ending.
Under the Old Testament dispensation, the oneness of God had to be deeply impressed upon Israel’s consciousness in the face of all polytheistic inclinations. It doesn’t take six semesters of Hebrew to realize that Israel, like us today, had an idolatry problem (as we do even today). From Adam to Jeroboam and on down, this was a problem. Thus, Vos thinks, before God decided to reveal His Triune identity, he ingrained deeply into Israel the concept of His unity.
As a sort of summary point, Vos notes that we must not imagine that Old Testament saints were able to read in the Old Testament alone everything we can read today in light of the new. In other words, the Old Testament saints did not have the clear New Testament revelation of God’s Triune nature as a lens through which to read the Old Testament.
Even with all this in mind, Vos does see traces of the Trinity in the Old Testament. In the Angel of the Lord, especially as spoken of in Judges 6 represents a kind of plurality in God, and Vos even sees *GASP* plurality in the Godhead from God’s name, Elohim, which has a plural suffix. Indeed, for Vos, this is both the plural of majesty and it expresses a plurality in the Godhead. Ultimately, Vos is a helpful caution to avoid seeing too much too certainly and too little too tentatively.