In chapter 3 of his Reformed Dogmatics (vol. 1), Geerhardus Vos set out 9 “traces of the doctrine of the Trinity…in the Old Testament.” Among the most noteworthy observations are those concerning the “Angel of the LORD” and the personification of Wisdom in the Proverbs:
1. The distinction between the names Elohim and Yahweh. Elohim is God as He works among both Israel and the heathen by creation and providence. Yahweh is God as He has made Himself known by theocratic guidance and revelation. Compare Genesis 1:1 with 2:4. Where God reveals Himself, He therefore bears another name, that is, one knows Him in that respect not only more than elsewhere but also as another.
2. The plural form of this name Elohim (see Eloah).
Since Peter Lombard many have found a proof for the Trinity in this form. For example, Luther, but not Calvin. Elohim, however, is used of Father and Son (see Psa 45:8); the name also appears for people and idols (Exod. 22:8, 1 Sam 28:13). The plural is to be understood intensively, as “heavens,” “waters” are extensive. It points to the inexhaustible fullness of God, and is therefore a pluralis majestatis in the deeper sense of the word.
3. The concept of the angel of the Lord מַלְאַךְ יְהֹוָה.
Concerning this are the following hypotheses:
a. The Angel of the Lord is a finite spirit, a created angel. Thus Augustine, Jerome, and later Kurtz and Delitzsch. This Angel, they say, can speak as if He were God, as the messenger speaks ex persona for the one who has sent Him and is identified with Him. However, how could such a messenger receive religious honor for the one who sent Him? Judg 6:11, 18, 22–23.
b. The Angel of the Lord is the Logos, the second Person of the Trinity. Thus Irenaeus, Tertullian, and later, Lutheran and Reformed dogmaticians (Calvin hesitates at some places, yet seems to choose 1 above), Hengstenberg. Some assume that the Logos has personally united Himself for a time with a created being.
c. The Angel of the Lord is not a person but only an impersonal appearance of God, a momentary entering of God into the sphere of the visible. מַלְאַךְ is to be understood as an abstract noun.
We accept the interpretation under 2 since only it does justice to all the givens. Additionally, however, we also note:
a. Those who shared in this appearance did not have a clear and distinct concept of the doctrine of the Trinity.
b. The Angel, the Messenger, was uncreated, the eternal Logos, but the visible form in which He revealed Himself was created, and the Logos was not personally united with it, as He was with the human nature assumed later.
The grounds for this interpretation are as follows:
a. The Angel speaks with God’s authority (Gen 16:13).
b. He is addressed as God (Gen 16:13).
c. He does divine works (Exod 23:20).
d. He has divine attributes (Gen 16:8).
e. He accepts divine honor (Josh 5:14).
f. He is distinguished from a created angel, Exodus 33, where the Angel of the Presence is distinguished from an ordinary angel (Isa 63:9; Deut 4:37).
g. His name alternates with the name Elohim (Zech 12:8).
h. The concept of Chokma, חָכְמָה, “wisdom,” as it appears in Proverbs 8:22 and following and Job 28:12–27. Here wisdom is personified, so that it becomes objective for God Himself and yet it stands in the closest relation to Him. It is the image of His thought, the perfect imprint of His inner existence—within Him and outside of Him at the same time. In the Prologue of the Gospel of John such things are said of the Logos.
4. To the word of God in the Old Testament are also ascribed divine attributes (e.g., Psa 33:4; Isa 40:8; Psa 119:105).
5. The doctrine of the Spirit of God in the Old Testament. The Spirit is the principle of the natural, rational, reasonable life of the world and thus represents the self-conscious immanence of God. He is also the Spirit of revelation. Finally, He is also the Spirit who lives with each believer (see Pss 51:13; 143:10). The Spirit acts as a person standing objectively vis-à-vis God (Isa 63:10; 48:16).
6. Old Testament passages in which God speaks of Himself in the plural. The church has always had a Trinitarian conception of these passages. The following are diverging sentiments:
a. It is a pluralis majestatis as the Oriental rulers used of themselves. There are no antecedents for this in Scripture. Only relatively late does something like this appear (Gen 20:15; cf. Ezra 6:8).
b. It is a pluralis communicationis by which God includes Himself together with the angels (cf. Isa 6:8); thus Philo, also the younger Delitzsch. However, in Gen 1:26 one cannot attribute an active part in creation to the angels.
c. It is a pluralis of self-generation, in which the subject considers and addresses Himself as object, so that the appearance of a plurality arises. See Hitzig. This is unproved, see Gen 2:18; Psa 12:5.
7. Old Testament passages where more than one person is expressly named; Pss 45:6–7; 110:1. Heb 1:8–9 shows that these passages must be understood in this way.
8. Passages that speak of three persons; Num 6:24–26; compare 2 Cor 13:14; Psa 33:6; Isa 61:1; 63:9–10.