The doctrine of the Trinity (Lat. trinitas “tri-unity” or “three-in-oneness”) is one of the most important doctrines of the Christian faith. However, the term “Godhead” is used which is found in Romans 1:20 and Colossians 2:9. Through the word “Godhead” the same idea is expressed by the term “Trinity,” that there are three living person in the Godhead. Let us not forget, there a warning against false teaching found in Paul’s letter to the Colossians. The apostle declares that the hearts of the believers are to be “knit together in love, and unto all riches of the full assurance of understanding, to the acknowledgment of the mystery of God, and of the Father, and of Christ; in whom are hid all the treasures of wisdom and knowledge.

There are two main ways of explaining the Trinity over the years:

Trinitarian speculations.

Trinitarian speculations consisted in interpreting the divine nature by analogies drawn from human nature. Many have tried to explain a threefold distinction within the Deity and attempts to explain it are not wanting in number. From the Cappadocian Fathers—Basil, Gregory of Nyssa, and Gregory Nazianzen—to the so-called Athanasian Creed or the more recent Hegelian and Barthian interpretations, not to mention Augustine, speculative Christian theologians, beginning with a humble confession or the incomprehensibility of the divine nature and the limitations of human speculation, cheerfully went on to interpret the relations of Father, Son, and Holy Spirit within the Deity, each one in terms of then-accepted discrimination of substance. “Hypostasis,” “nature” and “person” were among the preferred terms.
[one can see the excessively lengthy and complex course of trinitarian speculation through succeeding centuries (See sources below).

The Trinity of Revelation.

It is a declaration concerning God based on a revelation; not only on the self-disclosure of God but also on a disclosure of the truth of God. Therefore, it is an objective reality and, in the strictest sense, an affirmation of theology. The recognition of the Holy Spirit—as truly fully divine, parallel and equal to the Father is—first of all, the object of a revelation. This is how God wills to make himself known to man.

The divine Triad is met only in God’s revelation. It is therefore impossible to speak about God’s triune nature independent of the Scriptures. We must abide by the testimony of the OT and NT. This means that the Bible exceeds all the psychological and physiological analogies. When we speak of divine “persons” we do so because the Scriptures enforce this conclusion upon us. We do so because this is how the biblical writers under Inspiration try to make us understand the relationship existing between Father, Son, and Holy Spirit.

It’s unfortunate that the Trinity of speculation had triumphed over the Trinity of revelation and experience over the years. We hold fast to the Bible revelation of God. Who can know God except he reveals himself?

Three distinct Persons in the unity of God.

The word “person,” at this point, requires more particular notice. According to the ordinary rules of language-interpretation of the Scripture, nothing is more certain than that there is but one God. [See for instance Deut 4:39; 2 Ki 19:51; Ps 88:10; Is 44:6,9; Mk 12:29, 32]. This should never be forgotten. It is the very foundation of our doctrine of God.

By the same use of language rules, we also learn that there are three in whom we are to believe. The highest names and perfections are attributed to them throughout the Holy Writings. The Scriptures seem to indicate that these three are all persons because they are described as doing that which only intelligent agents or persons can do. Is not this sufficient authority for applying the term “persons” to them?

Finally, the same authoritative source tells us that they are distinct, not merely in relation to us, as Creator, Redeemer, and Sanctifier, but in relation to each other as Father, Son, and Holy Spirit. This is sufficient authority for calling them distinct Persons, although the danger always exists that one may tend to tritheism.

Just because some practices, terms or concept overlaps with paganism or mythology it doesn't mean that its origin or teachings are from or depended on them. For example, the Creation and Flood Stories of Bible are not from or dependent upon Babylonian accounts. Upon close examination, it is clearly shown that they are not the same. Ancient mythologies DO NOT drive biblical teachings, principles, concepts or practices.

We are not to surrender God’s revelation of himself "ancient mythology and mystery religions." It's not true that "more honest and recognized theological scholars of a Trinitarian background even openly admit and state that there was no such Trinity teaching in existence at the times of Acts and not until some time later."

God himself is a mystery, how much more the incarnation or the Trinity. However, that should not trouble us as long as the different aspects of these mysteries are clearly taught in Scripture. Even though we may not be able to comprehend logically the various aspects of the Trinity, we need to try and understand as best as we can the scriptural teaching regarding it. All attempts to explain the Trinity will fall short, “especially when we reflect on the relation of the three persons to the divine essence ... all analogies fail us and we become deeply conscious of the fact that the Trinity is a mystery far beyond our comprehension. It is the incomprehensible glory of the Godhead.” Therefore, we do well to admit that “man cannot comprehend it and make it intelligible. It is intelligible in some of its relations and modes of manifestations, but unintelligible in its essential nature.” (See Sources below). “There are many mysteries which we do not understand or can explain."

Trinitarian Confessions
Do the apostles think of the Holy Spirit as divine, as a divine person distinct both from the Father and from the Son?

Several passages can speak for themselves:

1. Paul mentions all three persons together. In one of his very earliest writings:

• “But we are bound to give thanks to God always for you, brethren beloved by the Lord, because God chose you from the beginning to be saved, through sanctification by the Spirit and belief in the truth. To this, he called you through our gospel, so that you may obtain the glory of our Lord Jesus Christ” (2 Thess. 2:13, 14).

2. It is evident that God, Christ, and the Spirit are in foremost in Paul’s mind. First Corinthians 12:4-6 agrees with this: “Now there are varieties of gifts, but the same Spirit and there are varieties of service, but the same Lord; and there are varieties of working, but it is the same God who inspires them all in every one.”
3. The triadic pattern is clearly seen. In an attempt to bring together basic values of the Christian faith Paul ended his second Epistle to the Corinthians with these words: “The grace or the Lord Jesus Christ and the love of God and the fellowship of the Holy Spirit be with you all” (2 Cor 13:14).

• When we place things side by side or in position, the three divine persons come together in a clear trinitarian confession. There are many other texts of Paul that reveals when closely examined the influence of a threefold pattern. See for instance Rom 15:30; Gal 4:6; 2 Cor 1:21, 22; Eph 3:14-16; Tit 3:4-6.

4. The Gospel of Matthew also ends clearly with the three persons found in their now traditional order:
   “Go therefore and make disciples of all nations, baptizing them in the name of the Father and of the Son and of the Holy Spirit” (Mt 28:19).

The fact that in these statements we have a trinitarian formula seems inescapable. I repeat it's erroneous to say that the doctrine of the Trinity is postbiblical and answers a problem which did not occur to the writers or the NT. Later as we look at the Trinity in Scripture… CM

Sources:

-- Louis Berkhof, Systematic Theology (Eerdmans, 1941), 88-89.
-- Henry P. vanDusen, Spirit, Son, and Father (New York, 1958), 149-177.
-- H.A.W. Turner, The Pattern of Christian Truth (London, 1954).] Note, also, the carefully documented Bampton lectures.