What is Trinitarianism? Is Trinitarianism biblical?

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).

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.

Here in this very majestic declaration of the Oneness of the Godhead, care is taken to state it consistently with the truth afterwards revealed concerning the Three Persons of the Godhead—Father, Son and Spirit. These Three Persons, of one Substance, completely united in thought, will, purpose, counsel, are not three Gods, but One God, not a tritheism, but a Holy Trinity. We cannot understand the mystery of all this, but this truth lies at the very foundation of the Christian faith.

Scripture is most plain, whatever unbelief may say, that there are three distinct persons in the Godhead, equal in power, majesty, and glory, each taking His own part in all that is done, whether in creation or redemption, yet ever acting in perfect unity and communion.

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.

We are, for example, taught in Matt. 28:19 that Father, Son, and Holy Spirit are comprehended under a single “name.” Though there are three Persons, there are not three names, but one; there are not three "grades," but one Tri-personal Unity.* The Lord also said, "I and the Father are One" (John 10:30); and "The Son can do nothing of Himself save whatever He sees the Father doing"; and "The Father knows Me, and I know the Father" (John 5:19; 10:15). These and other passages teach unity and community of nature between the Father and the Son.

It is a thousand pities that this should be so, for the sacred words have a tremendous import. The verse is one of the few where all the three Persons of the Triune God-head are named, the Holy Spirit being God equally with the Father and the Son. Not three Gods in one Person, but one God existing in three Persons.

THE TRINITY. In reference to this term the Father is God. Phil. 2:11; 1 Thess. 1:1, etc. The Lord Jesus is God. Isa. 9:6; Matt. 1:23; John 1:1; Rom. 9:5; Phil. 2:6; Col. 2:9; 1 Tim. 3:16; Heb. 1:8. The Holy Spirit is God: "the Spirit of God moved upon the face of the waters." Gen. 1:2. Ananias lied to 'the Holy Ghost,' 'unto God;' and Sapphira unto the 'Spirit of the Lord,' Acts 5:3-4, 9; 'Spirit of God.' 1 Cor. 2:11; 1 Cor. 3:16, etc. That there are three divine Persons (if we may so express it) is plain from scripture. The Father sent the Son, and He came to earth. The Father sent the Holy Spirit, and the Lord Jesus sent the Holy Spirit, and He came from heaven. He is a divine Person, of which there are many proofs (See HOLY SPIRIT). There is but one God.

Whilst it is true that nowhere in Scripture is it asserted in so many words that the Holy Spirit is God, yet the way in which the names of the Father, Son and Spirit are linked together, shows plainly the truth of the Deity of the Spirit with that of the Father and the Son. Believers are baptized “in the name of the Father, and of the Son and of the Holy Ghost” (Matt. 28:19). Could that formula be employed if it were not that the Spirit is God, as the Father is God and the Son is God? Then there is the charming benediction, “The grace of our Lord Jesus Christ, and the love of God, and the communion of the Holy Ghost, be with you all. Amen” (2 Cor. 13:14). One well-known passage we refer to, 1 Corinthians 12:11, where absolute sovereignty, an attribute only proper to Deity, is predicated of the Holy Spirit, “But all these works that one and the selfsame Spirit, dividing to every man severally AS HE WILL.” This is language only proper to God Himself. There is also one very striking passage where the fullest intimation of the Holy Trinity to be found in the Old Testament is given: “Come ye near unto Me, hear ye this; I have not spoken in secret from the beginning; from the time that it was there am I [a Divine Person] and now the Lord God and His Spirit has sent Me” (Isa. 48:16). (1) The Lord God, (2) His Spirit, (3) Me, three Persons in the Holy Trinity. How often the Lord when on earth spoke of Himself as the SENT One.

This baptizing is "unto the name of the Father, and of the Son, and of the Holy Ghost." The name, not the names, of the Triune. This is the Christian revelation of God; and what is not done in this way is not Christian. The "name" in Scripture gives the real character of what it stands for; and the name here is the truth of the Godhead as now made known to us: thus "baptism" and the "faith" are once more, as in Eph. 4 ("one faith, one baptism,"), connected together.