How is the Trinity not tritheism?

In the New Testament we have the revelation of God — Father, Son and Spirit — in the Son. It is there we learn that God is ONE (1 Timothy 2:5) yet THREE (Matthew 28:18-19). One in Essence or Essential Being; Three in Person. In the Old Testament The Lord our God is one Lord (Deuteronomy 6:4-5) in contrast with Polytheism. In the New Testament HE is One in contrast with Tritheism. Revelation may far outstretch our creature thought, but never goes against, or clashes with it. We may apprehend but never comprehend. We learn, therefore, that "God is One," is different in sense from what He is as Three. The former being impersonal and expressive of Him in His Eternal Omnipotence, Omniscience and Omnipresence. "Heaven is My throne, earth is My footstool." The latter shows us that within that Essence or Substance there are three Subsistances or Persons in holy and intrinsic relation dwelling together in LOVE. This we also learn is the nature of God from Whom comes the counsels of eternity, and follow on through Scripture to see how each One in the Holy Trinity engages in relation to and with the Others in carrying into effect the one eternal plan.

"For the threefold personality of God does not contradict His unity in any way: it shows the manner or condition of it. There are not three independent units side by side, on a level with each other, each almighty, each eternal, each finding in Himself the source of His own life. The unity of the three blessed Persons is not a similarity of character and qualities and powers … three Beings each of Whom is a God. (Will the reader carefully note the exact language employed here—"a God" not "God." Each is God, but not "a God."). It is true though inexpressible, unity of Three Persons … incapable of existence apart from one another. The life of all three is one and the same life, and it has but one source, not three. The very titles by which They are known to us, imply this. They are not proper names, like those of heathen divinities, but titles of relationship, which involve each other, and would be meaningless alone. Fatherhood is impossible without sonship, and sonship without fatherhood."

Thus we see that there could be no full revelation of God, but through the Son by the Spirit, and thereby of the Father. The full revelation of the one God is only thus - Father, Son, and Holy Ghost. This, this only, is what the one God is, one identity of will and being, so that they are essentially one and one only, yet distinct in willing and acting (and we can distinguish them in willing and acting: hence we commonly speak of persons), yet never willing or acting but in the common will and unity of nature.

So we must be careful in using the terms, first, second and third Persons in the Trinity, not to think there is any difference in importance. The Father is God; the Son is God; the Spirit is God—the Spirit equal in nature and substance to the Father and the Son. If the three Persons of the Godhead are each of them God, it does not follow that there are three Gods. That were impossible. There can be only one God, supreme and unique. Orthodox Christendom believes in three Persons in the Godhead, yet one God, indivisible and unique—the three Persons in the Godhead with one will, one purpose, each sharing to the full every thought and desire and purpose in the minds of the others. We may not, nay cannot, comprehend this. It is a mystery hidden in the Godhead, yet the Godhead is pleased to reveal Itself as Father, Son, and Holy Spirit.

How, then, it may be asked, do we sustain our doctrine of eternal generation and at the same time obviate such a conclusion? We sustain it thus. We have already shown that there is a distinction between the Essence of God, which is one and self-existent, and the Personality of the Three Persons in the Godhead. Which is threefold, and thus intercommunicative, and so far dependent. We have to lament the inadequacy of language, or at least of our own language, to set such sublime mysteries forth; but the doctrine of a Trinity in Unity can only be so defended. The Unity of God implies self-existence; the Trinity in Unity implies relationship. Thus as regards the Unity of Essence Christ is self-existent; but as regards the Trinity He is begotten. He is therefore not a begotten God, though He is a begotten-Son. This explanation may be called mystical and obscure; but on such deep and incomprehensible subjects all thought fails and all language falters. Yet as we are sometimes called upon to state or defend our views of divine truth, it is desirable to have clear views of what we believe, and to express them as plainly as possible. We believe, then, that there are Three Persons in the Godhead, and that these are distinguished from each other by certain personal relationships, and that these personal relationships are not covenant titles, names, or offices, but are distinctive and eternal modes of existence. We are thus preserved from Sabellianism on the one hand, which holds that there is but one God with three different names; and Tritheism on the other, which makes three distinct Gods. But believing in a Trinity of Persons, in the Unity of the divine Essence, we say that the father is a Father as begetting; the Son is a Son as begotten; the Holy Spirit is a Spirit as proceeding. If, as imputed to us, we were to say that the Son is “a begotten God,” we should deny Him self-existence in His Essence, as One with the Father and the Holy Spirit; as if we should say that He is a Son by office or by His incarnation, we should deny, as Mr. Crowther does, His true, proper and actual Sonship. To sum up the whole in a few words, it is in His Person, not in His Essence, that He is the only-begotten Son of God. Dr. Gill has opened up this distinction with his usual clearness and ability in the following extract from his “Body of Divinity”:

When I say it is by necessity of nature, I do not mean that the divine nature, in which the divine Persons subsist, distinguishes Them; for that nature is one and common to Them all. The nature of the Son is the same with that of the Father; and the nature of the Spirit the same with that of the Father and the Son; and this nature, which They in common partake of, is undivided; it is not parted between Them, so that one has one part, and another a second, and another a third; nor that one has a greater and another a lesser part, which might distinguish Them, but the whole fullness of the Godhead is in each.

The truth as to the Deity is not that there are Gods—three supreme and omnipotent Beings, each having His own life and acting from Himself—but three in one—Father, Son and Holy Spirit—One God; and though for the sake of accommodation we use the word Person, and speak of three Persons in the Godhead, yet there are not three Persons as we understand persons. Such as Abraham, Isaac, and Jacob were three persons; each having his own separate life.

This truth of the eternal relationship of Father, Son and Holy Spirit is vital. To have three beings coequal in deity without relationship would be three Gods, not one Triune God.

In human language when we speak of a person, we think of separate entity, separate existence, separate will, different characteristics, thoughts and plans peculiar to each person, not shared with any others. Carry that human thought into the subject before us, and the truth of the Trinity is entirely perverted and lost. Instead of the Trinity—Father, Son and Spirit, ONE God—we should have three Gods, an absolute impossibility, for there can only be one God, unique and incomprehensible.

Moreover in Genesis 1:1, the verb, created, following the plural noun, is in the singular, showing that there is only one God, though there are three persons in the Godhead, a plural unity, if we may so phrase it. There is one particularly interesting example of the use of the word, God, in the plural, we would draw attention to. In the special affirmation of the oneness of God in connection with the solemn occasion of the giving of the law, we read:

This clearly shows that whilst Scripture affirms that there are three distinct Persons in the Godhead, yet there are not three Gods, but one; not a trinity of Gods, but a triune God.

Our title at the head of this paper is one such. Yet there is abundance of teaching in the Holy Scriptures that God reveals Himself as Father, Son and Holy Spirit, not three Gods, but a Triune God, though Scripture teaches that the Father is God, the Son is God, the Holy Spirit is God, yet one God indivisible.