I believe that the ontological confession that the logos (Jesus) precedes the OT is what provides the warrant to do trinitarian or Christological readings of the OT.1 Because of the complexities that surround this subject, one must first remember that God’s being precedes our understanding. We should not allow our preconceived notions of God or our own theological predilections to shape our understanding of his ways and being. We need to let the Scriptures speak and reveal what God has already said about himself in creation and redemption. Since there will always be an element of mystery in our study of God’s being and ways, we must be humble and teachable when we study doctrines like the Trinity which cannot be fully fathomed by the human mind. However, this does not mean that there is nothing to know about the Trinity, most especially the Son’s relationship with the Father and his being. Mark Gignilliat notes that the Apostles assumed the canonical givenness of the OT as their Scriptures and that the church confesses that the God of Israel’s identity is bound up in the person and work of Jesus Christ and the Holy Spirit who attests to His work.2 Hence, he is right to conclude that to talk about Jesus and the Holy Spirit demands to talk about the God of Israel. It is important to understand that these assumptions were not done by proof-texting passages but through a careful exegesis of the Bible. By applying the rule of faith and a total reading of Scripture it becomes clear that the OT warrants trinitarian grammar.
Moreover, the OT is able to witness to a Triune God by first showing that Israel’s God is to be worshiped alone. He does not share his glory with any other name (Isa. 45:27). The first half of the Ten Commandments attest to this. God made it clear to Moses and the Israelites that He will judge them if they worship other gods. The basis of God’s judgment was his law and character.
Secondly, the revelation of the divine Name demands understanding of that Name in the context of his soteric movement toward his people.
God was able to reveal his being through his acts in creation and redemption. In fact, “God” is in plural form in Genesis 1:1 and implies that the Triune God was responsible for creating the world. Moreover, the Triune God was the one who created Israel out of nothing. She was elected not because of her might but because of God’s steadfast love. The Triune God was also involved in the redemption of Israel. She was delivered from Egyptian captivity and protected from her enemies by God’s right hand. Furthermore, the theophanies in the OT point to the fact that God appeared to his leaders and people in human form.
Thirdly, within the Oneness of God there is a plurality of Otherness.
While the Greek world did not have room for trinitarian logic, the Old Testament did.
For example, the “Angel of the Lord” in the OT not only appeared as a messenger but also appeared to human beings in human form in Genesis, Judges, and Kings. The appearances and actions of the Angel of the Lord in the OT demands and provides Trinitarian grammar because He is seen as divine.
Moreover, I agree with Gignilliat’s argument regarding the OT’s witness to a triune God/the person of Jesus because I have realized that a thorough and proper exegesis of the OT leads to this conclusion: there is one God in three persons.3 Moreover, when Irenaeus’ rule of faith and total reading of Scripture is applied in the study of the OT and its relationship to the NT, it becomes apparent that both the Son and the Spirit are consubstantial with the Father. While the Apostles did not use the word “trinity” in their writings, nor is it found in the OT, the application of OT prophecies concerning Jesus’ incarnation and divinity imply that the Father, Son, Holy Spirit are of the same substance. Lastly, Paul’s epistles are replete with verses that reveal Jesus is consubstantial with the Father (Rom 1:1-4, 9:5; Gal 4:4-5; Col 1:14-15).
1 Mark Gignilliat, Video Lecture. Knox Theological Seminary, Ft. Lauderdale FL, Lesson 04, August 23, 2017.