Belief in a God of three persons is one of the most demanding biblical teachings. Christianity is the only world religion that makes this claim. The doctrine of the Trinity is truly distinctive of the Christian faith, crucial because it deals with who God is, what He is like, and how He works. Christians believe the doctrine is necessary to do justice to the testimony of Scripture, the primary source of our knowledge of God. We must speak concerning God in the terms He uses. Biblical evidence has three facets: (a) there is one God; (b) three-in-oneness; and (c) three persons who are God.
Christianity emerged from the ancient Hebrews, who were rigorously monotheistic (and remain so today). Writers of the Old Testament address this, sometimes quoting God directly. The Decalogue begins with the divine statement: “I am the Lord your God, who brought you out of Egypt, out of the house of bondage. You shall have no other gods before Me” (Ex. 20:2, 3). Deuteronomy 6:4 contains the definitive monotheistic statement, initially insisted within a polytheistic world: “Hear, O Israel: the Lord our God, the Lord is one.”
The New Testament continues Old Testament sentiments, such as Paul (1 Cor. 8:4) and James (James 2:19). What then caused these monotheistic Jews and Christians to declare belief in the three-personed Godhead? It was the biblical witness of three divine persons.
God refers to Himself both as “He” and “Us.” In the Old Testament the plural form of one of the nouns for God (’elohim) is quantitative: “Let Us make man in Our image.” The plural appears both with the verb “Let Us make” and the possessive suffix “Our” (Gen. 1:26; 11:7). Isaiah, in vision, hears the Lord: “Whom shall I send, and who will go for Us?” (Isa. 6:8).
In Genesis 2:24 man and woman are to become one (’echad), a union of two separate entities. Significantly, the same word is used of God in Deuteronomy 6:4. Marriage and God’s nature are both described as a plural unity.
Three divine persons are often linked together (Isa. 42:1; 61:1, 2; 63:8-11). The angel tells Mary that her child will be called holy because the Holy Spirit will come upon her (Luke 1:35). At the baptism of Jesus (Matt. 3:16, 17) three divine persons are present. Jesus links His miracles to the Spirit of God’s power (Matt. 12:28). Because of the Great Commission, new disciples are baptized in the singular “name” of the three persons: Father, Son and Holy Spirit (Matt. 28:19).
Pronounced evidence can be found in the gospel of John. Jesus declares: The Son is sent by the Father (14:24), coming from Him (16:28). The Spirit is given by the Father (14:16), sent from the Father (14:26) and proceeds from the Father (15:26). The Son prays for the coming of the Spirit (14:16); the Father sends the Spirit in the Son’s name (14:26); the Son sends the Spirit from the Father (15:26). The Spirit’s ministry continues the Son’s, bringing to remembrance what the Son has said (14:26), bearing witness to the Son (15:26), declaring what He hears from the Son, glorifying the Son (16:13, 14). Jesus prays that His disciples may be one as He and the Father are One (17:21).
Peter names three divine persons at Pentecost: “Exalted to the right hand of God, and having received from the Father the promised Holy Spirit, He poured out this. . . . Let every one of you be baptized in the name of Jesus Christ . . . and you shall receive the . . . Holy Spirit” (Acts 2:33-38).
Paul often speaks of the triune God, relating salvation to the three Persons of the Trinity (2 Cor. 1:21, 22). The form as well as content of his writing communicates his belief in the book of Romans: God’s judgment upon everyone (1:18–3:20); justification through faith in Christ (3:21–8:1); life in the Spirit (8:2-30). Paul also includes them in his benedictions: “The grace of the Lord Jesus Christ, and the love of God, and the communion of the Holy Spirit be with you all” (2 Cor. 13:14). Similar formulaic expressions appear also in Peter’s and Jude’s epistles (1 Peter 1:1, 2; Jude 20, 21).
