"And the Catholic Faith is this: That we worship one God in Trinity, and Trinity in Unity; Neither confounding the Persons: nor dividing the Substance. For there is one Person of the Father: another of the Son: and another of the Holy Ghost. But the Godhead of the Father, of the Son, and of the Holy Ghost, is all one: the Glory equal, the Majesty coeternal. Such as the Father is: such is the Son: and such is the Holy Ghost." -- The Athanasian Creed
"We confesse and acknawledge ane onelie God, to whom onelie we must cleave, whom onelie we must serve, whom onelie we must worship, and in whom onelie we must put our trust. Who is Eternall, Infinit, Unmeasureable, Incomprehensible, Omnipotent, Invisible: ane in substance, and zit distinct in thre personnis, the Father, the Sone, and the holie Gost." -- The Scotch Confession of Faith, A.D. 1560.
"There is but one living and true God, everlasting, without body, parts, or passions; of infinite power, wisdom, and goodness; and Maker, and Preserver of all things both visible and invisible. And in unity of this Godhead there be three Persons, of one substance, power, and eternity: the Father, the Son, and the Holy Ghost." -- Article I of the Church of England.
"For He so proclaims Himself the sole God as to offer Himself to be contemplated clearly in three persons. Unless we grasp these, only the bare and empty name of God flits about in our brains, to the exclusion of the true God. Again, lest anyone imagine that God is threefold, or think God's simple essence to be torn into three persons, we must here seek a short and easy definition to free us from all error." -- John Calvin, Institues (He then discusses the subject for the next 37 pages)
"The phenomena (to use the Baconian phraseology) with which we have here to deal are, on the one hand, the clearly revealed fact that there is but one God; and, on the other, the no less clearly revealed fact that there are three to whom the attributes and qualities of Deity in the highest sense are ascribed, the Father, the Son, and the Holy Ghost." -- W. Lindsay Alexander, System of Biblical Theology
"All the divine attributes as well as the properties of personality are ascribed to each person of the Godhead with so much certainty and frequency, that the fact of a triune mode of existence cannot be doubted by an unprejudiced mind. On the other hand, disclosures equally plain and numerous are made which present God as essentially One. These two averments of the Bible are alike authoritative and, therefore, to the same degree demanding as to their recognition. Though no finite mind has ever comprehended how three Persons may form but one Essence, that precise truth is the testimony of all parts of the Bible." -- Lewis Sperry Chafer, Systematic Theology
"The triune mode of existence of the three Persons who form one Essence belongs to a category of ultimate facts and the inexplicable feature is not to be confounded with the evidence for the abstract and actual truth itself. No argument has been advanced against the trinitarian conception other than that it does not conform to the limitations of the mind of man." -- Lewis Sperry Chafer, Systematic Theology
"As he that denies it may lose his soul; so he that too much strives to understand it may lose his wits." -- Dr. Robert South (1634-1716)
"Quite in keeping with the truth that God is one Essence in which three Persons subsist, is the fact that the Angel of Jehovah is at times One other than Jehovah, and at other times He is Jehovah Himself." -- Lewis Sperry Chafer, Systematic Theology
"The inner part of the Jewish sanctuary was called the holy of holies, that is, the holy place of the Holy Ones; and the number of these is indicated, and limited to three, in the celebrated vision of Isaiah, and that with great explicitness. The scene of that vision is the holy place of the temple, and lies therefore in the very abode and residence of the Holy Ones, here celebrated by the seraphs who veiled their faces before them. And one cried unto another, and said, "Holy, holy, holy is the LORD of hosts." This passage, if it stood alone, might be eluded by saying that this act of Divine adoration here mentioned, is merely emphatic, or in the Hebrew mode of expressing a superlative; though that is assumed, and by no means proved. It is however worthy of serious notice, that this distinct trine act of adoration, which has been so often supposed to mark a plurality of persons as the objects of it, is answered by a voice from that excellent glory which overwhelmed the mind of the prophet when he was favoured with the vision, responding in the same language of plurality in which the doxology of the seraphs is expressed. "Also I heard the voice of the Lord, saying, Whom shall I send, and who will go for US?" But this is not the only evidence that in this passage the Holy Ones, who were addressed each by his appropriate and equal designation of holy, were the three Divine subsistences in the Godhead. The being addressed is the "LORD of hosts." This all acknowledge to include the Father; but the Evangelist John,xii,41, in manifest reference to this transaction, observes, "These things said Esaias, when he saw his (Christ's) glory and spake of him." In this vision, therefore, we have the Son also, whose glory on this occasion the prophet is said to have beheld. Acts xxviii,25, determines that there was also the presence of the Holy Ghost. "Well spake the Holy Ghost by Esaias the prophet unto our fathers, saying, Go unto this people and say, Hearing ye shall hear and not understand; and seeing ye shall see and not perceive," &c. These words, quoted from Isaiah, the Apostle Paul declares to have been spoken by the Holy Ghost, and Isaiah declares them to have been spoken on this very occasion by the "LORD of hosts." "And he said, Go and tell this people, Hear ye indeed but understand not, and see ye indeed but perceive not," &c.
Now let all these circumstance be placed together - THE PLACE, the holy place of the Holy Ones; the repetition of the homage, THREE times, Holy, holy, holy - the ONE Jehovah of hosts, to whom it was addressed, - the plural pronoun used by this ONE Jehovah, US; the declaration of an evangelist, that on this occasion Isaiah saw the glory of Christ; the declaration of St. Paul, that the Lord of hosts who spoke on that occasion was the HOLY GHOST; and the conclusion will not appear to be without most powerful authority, both circumstantial and declaratory, that the adoration, Holy, holy, holy, referred to the Divine three, in the one essence of the Lord of hosts. Accordingly, in the book of Revelation, where "the lamb" is so constantly represented as sitting upon the Divine throne, and where he by name is associated with the Father, as the object of the equal homage and praise of saints and angels; this scene from Isaiah is transferred into the fourth chapter, and the "living creatures," the seraphim of the prophet, are heard in the same strain, and with the same trine repetition, saying, "Holy, holy, holy, Lord God Almighty, which was, and is, and is to come."
In his chapter entitled "Proof of the Trinitarian Doctrine," under the section entitled "The Trinity and the Names of God," Chafer says the following:
"While the different names of the Persons in the Godhead are everywhere fully employed throughout the New Testament, the complete designation for God as revealed in the New Covenant is declared in, and as a part of, the Great Commission, to wit: 'Go ye therefore, and teach all nations, baptizing them in the name of the Father, and of the Son, and of the Holy Ghost' (Matt. 28:19). As baptism stands as the initial act of a believer in a public witness for Christ, so, on that threshold, the full title is proclaimed of the God into whose fellowship the candidate enters. In this connection, it is significant that the first public appearance of Christ was that of His baptism, and that, though no formula is recorded as having been pronounced over Christ by John on that occasion, the three Persons of the Godhead were present and identified. The Father owned the Son - 'This is my beloved Son'--; the Son was visibly present; and the Spirit was seen to descend upon Christ in the form of a dove. Direction is given in the Great Commission that baptism should be administered in the name, not names - the one name of the Father, and of the Son, and of the Holy Spirit. The phrase, the name, is a strong declaration of the divine unity which subsists as Father, Son, and Spirit. The ordinance in view is to be performed by the authority of that incomparable name, but that name is threefold." --Systematic Theology, Volume I, pages 303-304.
Click here to see an outline of New Testament proofs for the Doctrine of the Trinity (outlined from Chafer's section on the subject).
"Some of our readers may be surprised to hear that there are men professing to be Christian who flatly deny the personality of the Spirit. We will not sully these pages by transcribing their blasphemies, but we will mention one detail to which appeal is made by the spiritual seducers, because some of our friends have possibly experienced a difficulty with it. In the second chapter of Acts the Holy Spirit was said to be "poured out" (v. 18) and "shed abroad" (v. 33). How could such terms be used of a Person? Very easily: that language is figurative, and not literal; literal it cannot be for that which is spiritual is incapable of being materially "poured out." The figure is easily interpreted: as water "poured out" descends, so the Spirit has come from heaven to earth; as a "pouring" rain is a heavy one, so the Spirit is freely given in the plentitude of His gifts." --Arthur W. Pink, The Holy Spirit, pp. 10-11.
"The Messianic character of Psalm 45 cannot be questioned. Its closing verse is a promise and a prophecy, 'I will make thy name to be remembered in all generations: therefore shall the people praise thee for ever and ever.' Because of all that is disclosed in the name of the Messiah, He shall be praised in all generations. Large indeed is the sum total of all His names, His titles, and His descriptive designations. Because of His incarnation, His work in redemption, and His multiplied relationships, the number of His appellations exceeds those of the Father, the Spirit, and all the angels so far as these are revealed. As is true of each Person of the Godhead, the names of the Second Person are a distinct revelation. It is probable that almost every essential truth resident in the Second Person is expressed in some specific name, e.g., Emmanuel speaks of His incarnation relationships, Jesus of His salvation, the Son of man of His humanity, the Son of God of His Deity, Lord of His authority, the Son of David of His throne rights, Faithful and True of His manifestations, and Jesus Christ the Righteous of the equity with which He meets the condemnation due the Christian because of sin." -- Lewis Sperry Chafer, Systematic Theology, Volume I, page 332.
"It was Jehovah who was pierced (Zech. 12:10); God who purchased the Church with His own blood (Acts 20:28); it was ho Despotes -- "the High Lord" -- that bought sinners (2 Pet. 2:1); and the Lord of Glory was crucified (1 Cor. 2:8)." -- Lewis Sperry Chafer, Systematic Theology, Volume I, page 279.
"The doctrine of the trinity is not a result of mere speculation, not a theory or hypothesis spun by theologians out of their own fancies, still less, as some eminent writers would maintain, the result of the importation of Greek metaphysics into Christian theology. It is, in the first instance, the result of a simple process of induction from the facts of the Christian revelation....The triune conception of God is justified, when it is shown to be the conception which underlies the triune revelation God has given of himself [sic], and the triune activity in the work of redemption." -- Dr. James Orr, The Christian View of God and the World, pp. 303-4.
"Whatever may have been the force of the Old Testament revelation regarding the Holy Spirit and that under the prescribed limitations which a divinely arranged progress of doctrine imposed, it is evident that the full manifestation of His personality and Deity, the full import of His equal position in the Godhead, and the specific scope and objective in His work, are declared in the New Testament. That the truth concerning the Spirit forms a major theme in practically every book of the New Testament is a fact which must be arresting to all who are concerned. It is outside the range of the scope of this present discussion to attempt at this point any general presentation of so vast a theme except to say, that, as pointed out above, it is the same Holy Spirit who is disclosed in the New Testament who appears so fully in the Old Testament, though very much truth is added by the New Testament message. The progress of doctrine is in evidence and not any change in the Person being considered. Without an expanding prelusion the Spirit, as God Himself, is seen in the New Testament in the full ordered majesty of His own divine Person. He is presented as One who is coming into the world and that by the promise of both the Father and the Son (John 14:26; 16:7), and thus He came on the Day of Pentecost. In view of the Old Testament revelation which avers that He was already in the world, a problem arises about the meaning of these promises that He would come into the world. The answer is hidden in the distinction which obtains between and omnipresence, which is the mode of the Spirit's presence in the world before the Day of Pentecost, and residence, which is the mode of the Spirit's presence after Pentecost. It yet remains to occur that He whose residence is now in the Church, the temple of living stones (Eph. 2:18-22), will as definitely leave the world when His temple is removed; and yet, after being removed from the world as a resident, He will still be in the world as the omnipresent One. This it will be recognized is no new prcedure, since the same is true of the Second Person who was first in the world in the omnipresent sense and, after being resident here for thiry-three years, left the world, but still retained the omnipresent presence since He indwells every believer (Col. 1:27) and is attending wherever two or three are met in His name (Matt. 18:20)." -- Lewis Sperry Chafer, Systematic Theology, Volume I, pages 410-411.