What is the Holy Trinity in simple terms?

I learn from the scriptures that there is one living God,1 fully revealed to us in Christ,2 and known through Him as Father, Son, and Holy Ghost,3 in the unity of the Godhead, but revealed as distinctively willing,5 acting,6 sending, sent,7 coming,8 distributing,9 and other actings; or, as habitually expressed amongst Christians, three persons in one God, or Trinity in Unity. God is the Creator of all things; but the act of creating is personally attributed to the Word and the Son, and the operation of the Spirit of God.10

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.

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.

Divine revelation tells us of a triune God, that is three Divine Persons yet One God. The Bible presents three in One and One in Three—Father, Son and Spirit, the Triune God, completely One in power, will, and knowledge.

The revelation of God is complete, and we know God now as Father, Son and Holy Ghost: three Persons yet one God. It was this that came into full manifestation when Jesus was here, for “in Him all the fullness [of the Godhead] was pleased to dwell” (Col. 1:19, see also 2:10. Darby's N.T.) and “God was manifest in the flesh” (1 Tim. 3:16).

The revelation of God is complete, and we know God now as Father, Son and Holy Ghost: three Persons yet one God. It was this that came into full manifestation when Jesus was here, for "in Him all the fulness (of the Godhead) was pleased to dwell" (Col. 1:19, see also Col. 2:10, Darby's N.T.), and "God was manifest in the flesh" (1 Tim. 3:16).

There are three divine persons: the Father, the Son and the Holy Spirit. Each of them is ‘God’.

For the Son, see questions 2 and 3. For the Father, there are so many references to Him as the ‘God and Father’ (e.g. Eph. 1:3). The Spirit is eternal (Heb. 9:14), omnipresent (Ps. 139:7) and co-equal (‘on the same level with’) the Father and the Son (Mt. 18:19; 2 Cor. 13:13; Rev.1:4).

The revelation that we have of God conveys to us the great truth that He is Father, Son, and Holy Ghost; three persons, yet one God, and God is love. This is what He is in His nature, what He is in His very being. There is nothing but love between those Divine and Eternal Persons. "Thou lovedst Me," says Jesus to the Father, "before the foundation of the world" (John 17:24). "God is Love" is the only absolute appellative that is used of the supreme Being; and what a wave of infinite happiness and indescribable joy overwhelms the soul as we meditate upon the marvellous fact that love is the nature of the One with whom we have to do. That "God is light" the Word also declares, but we are also said to be light, and therefore I take it that light is a more relative term, and not so absolute as love.

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.

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.

“To come to the point—it is the personal relations or distinctive relative properties which belong to each Person which distinguish Them from one another; as paternity in the First Person, filiation in the Second, and spiration in the Third; or, more plainly, it is begetting Psalm 2:7 which peculiarly belongs to the First, and is never ascribed to the Second and Third, which distinguishes Him from Them both, and gives Him; with great propriety, the Name of the Father; and it is being begotten, that is the personal relation, or relative property of the Second Person, hence called the only begotten of the Father (John 1:14), which distinguishes Him from the First and Third, and gives Him the name of the Son; and the relative property, or personal relation of the Third Person is, that He is breathed by the First and Second Persons; hence called the breath of the Almighty, the breath of the mouth of Jehovah the Father, and the breath of the mouth of Christ the Lord, and which is never said of the other Two Persons, and so distinguishes Him from Them; and very pertinently gives Him the name of the Spirit, or breath” (Job 33:4; Psalm 33:6; 2 Thessalonians 2:8). “Body of Divinity,” Book 1., ch. 28.

It will be seen from these extracts that a distinction is drawn between Essence and Person; but as some of my readers may feel a difficulty in gathering up the distinction between the two, I submit the following idea as an illustration, but, be it remembered, only as an illustration. Human nature is distinct, or at least distinguishable, from the individual men and women who in common possess that nature. Thus we may say that, human nature is common to alt men and women, and yet that men and women are distinct from one another as individuals. So, in a high and mysterious sense, the Essence of Deity, which is self-existent, may be distinguished from the Persons in the Deity, who sustain to each other a peculiar and eternal relationship. In Their Essence They are One, in Their Personality They are Three; in Their Essence They are self-existent, in Their Personality They subsist, the Father as Father to the Son, the Son as Son to the Father, the Holy Spirit to both as proceeding from the Father and the Son. Thus we establish a Trinity in Unity. “Hear, O Israel, the Lord our God is one Lord.” There is the unity of the divine Essence. “There are Three that bear record in heaven, the Father, the Word, and the Holy Spirit.” There we have the Trinity of Persons in the divine Essence, “for these Three are One” (1 John 5:7).