The matter of the trinity of the Godhead—the Father, Son, and Spirit—was already revealed in the Old Testament:

1. The first sentence in the Old Testament states, "In the beginning God created the heavens and the earth" (Gen. 1:1). In the original language the subject "God" is triple in number, whereas the verb is singular in number. This contains the meaning that God is three-in-one.

2. In Genesis 1:26, not only is the word "God" used in triple number in the original language, but God speaks of Himself as "us." Subsequently, the Old Testament speaks several times in this manner, as we have pointed out previously. This explicitly declares that the persons of God are plural. But here, in Genesis 1:26, the word used for the "image" of God in the original language is singular. Although God is "us," plural, yet the "image" of "us" is singular, one. Therefore, this also contains the meaning of God being three-in-one.

3. In Exodus 3:6 the Lord said to Moses, "I am the God of thy father, the God of Abraham, the God of Isaac, and the God of Jacob." This passage reveals that God as the God of the patriarchs is threefold. With the God of Abraham the emphasis is on the Father; with the God of Isaac the emphasis is on the Son; and with the God of Jacob the emphasis is on the Spirit. (Cf. The God of Abraham, Isaac, and Jacob, also titled, Changed into His Likeness.) Therefore, the name for Himself which God revealed here also contains the meaning of three-in-one. Although He is one God, yet there is the matter of threefoldness, that is, the threefold person—the Father, the Son, and the Spirit.

4. In Numbers 6:24-26 the Lord commanded the priests in the Old Testament to bestow a threefold blessing upon the children of Israel. This undoubtedly is because He, the God who bestows the blessing, is one in three persons. In the first place, to "bless thee" and "keep thee" is evidently the work of God the Father; in the second place, to "shine upon thee" and "be gracious unto thee" is manifestly the work of God the Son; and in the third place, to "lift up His countenance upon thee" and "give thee peace" is undoubtedly the work of God the Spirit. Therefore, this means that the Triune God—the Father, the Son, and the Spirit—may bless, be gracious, and give peace to His chosen people.

5. Not only does the Old Testament say that the priests on earth bestow a threefold blessing on the people of God in His name, but it also says in Isaiah 6:3 that the seraphim in the heavens give threefold praise to God, saying, "Holy, holy, holy." The reason they praise God by repeating the word "holy" three times is, without any doubt, because the God whom they praise is one-in-three. Then following, in verse 8, it says that the God whom they praise speaks of Himself as "us," plural, which means He has a threefold Person.

6. The Old Testament mentions several times that the angel of the Lord in human form (who, in the New Testament age, is the Christ who became flesh and took the form of a man) is the Lord Himself (Exo. 3:2-6; Judg. 6:11-24; 13:15-24; Zech. 1:11-12; 2:8-11). It seems that the angel of the Lord and the Lord are two, but actually They are one. This must also be due to the fact of the three persons of the Godhead, just as in the New Testament Christ and God are two, yet also one.