The doctrine of the Trinity, though revealed and mentioned but not explicitly articulated in Scripture in terms that some demand, fundamentally stems from the biblical teaching that there are characteristics and attributes of personhood for God the Father, Holy Spirit, and Son. The most essential basis for the doctrine of the Trinity is that Scripture clearly, explicitly, and repeatedly declares the deity of Jesus Christ.1 Moreover, the Scripture unmistakably refers to the Holy Spirit as God and attributes characteristics belonging to God alone.2 Since the Scripture also declares that the Lord is one and there is no other,3 by this we know that indeed God is one in perfect and incomprehensible unity of three persons: Father, Son, and Holy Spirit. Each member of the Triune Godhead, or Trinity, is revealed with qualities of a “person,” if we consider the qualities of knowledge, feeling, and volition as those belonging to a person. Each one is all-knowing, each one loves, and each one wills.4 Understanding the unique and exclusively superlative position that the one true God alone possesses, as revealed in Scripture, we see that God is thus revealed in three distinct persons, each person is fully God, and there is only one God. This is foundational to the faith of the New Covenant through Christ. Thus, it is in the name (singular in the Greek text) of the Triune God that we are commissioned to baptize new disciples in the distinctive identity of the Christian faith.5
“In the doctrine of the Trinity, we encounter one of the truly distinctive doctrines of Christianity. Among the religions of the world, the Christian faith is unique in making the claim that God is one and yet there are three who are God. . . . The doctrine of the Trinity is crucial for Christianity. It is concerned with who God is, what he is like, how he works, and how he is to be approached. Moreover, the question of the deity of Jesus Christ, which has historically been a point of great tension, is very much wrapped up with our understanding of the Trinity.” (Erickson, 347).
“Of course Christians agree with Jews and Muslims that there is only one God, but much to the latters’ bewilderment, they insist that this one God is also a Trinity of persons. To make matters more complicated, Christians do not believe that the Trinity is formed by cutting God up into three pieces, or by regarding him from three different angles. . . . Christians insist that each of the persons is fully God in his own right, while remaining at the same time distinct from the others. To Jews or Muslims it might appear that Christians affirm everything they believe about God, and then go on to add two extra persons, whose existence seems to contradict an otherwise common affirmation of monotheism.” (Bray, 115).
“Sadly, many nominally orthodox Christians are unitarian in all but name. They regard the Father as God, Jesus as divine but somehow inferior to God, and the Holy Spirit as an impersonal force, whom they may quite happily refer to as ‘it.’” (Bray, 124).
God is three persons in one essence. The Divine essence subsists wholly and indivisibly, simultaneously and eternally, in Father, Son, and Holy Spirit.
Moreover, we may confidently assert that the Trinity appears to belong to the inner life of God and thus known only by those who share the life that He alone gives through Jesus Christ—the fullness of His self-revelation. “To know the Trinity is to know the gospel, to have passed from the old dispensation to the new” (Bray, 141). It is through the New Covenant that the revelation of the Trinity is possible (cf. Gal 4:6). “As long as we look at God on the outside, we shall never see beyond his unity; for, as the Cappadocian Fathers and Augustine realized, the external works of the Trinity are undivided. . . . This means that an outside observer will never detect the inner reality of God, and will never enter the communion with him which is promised to us in Christ. Jews may recognize God’s existence and know his law, but without Christ they cannot penetrate the mystery of that divine fellowship which Christians call the Holy Trinity” (Bray, 119).
For more information, please consider the sources listed on our Bibliography of Works on the Trinity.
See also, "Christ as God."
 Isaiah 7:14; 9:6; 44:6; 48:12-16; Matthew 1:23; John 1:1, 14, 18; 8:58; 10:30; 20:28. Also see "Christ as God"