The Indispensibility of the Trinity

Because of their use in baptism, our Lord’s words at the very end of Matthew’s Gospel are among the most familiar in the New Testament. Meeting with his remaining eleven disciples, the resurrected Jesus told them:

All authority in heaven and on earth has been given to me. 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, teaching them to observe all that I have commanded you. And behold I am with you always, to the end of the age [Matt. 28:18-20; our emphasis].

Less familiar to many of us is the Apostle Paul’s benediction at the end of his second letter to the Corinthians, where he prays, “The grace of the Lord Jesus Christ and the love of God and the fellowship of the Holy Spirit be with you all” (2 Cor. 13:14).

As our other articles note, these passages are crucial for understanding the doctrine of the Trinity. Today, few Christian doctrines are as misunderstood or ignored as this one. Most of us have heard Sunday school teachers attempt to explain how God can be three-in-one. For instance, most of us have heard someone say, “The three members of the Trinity are like the three forms in which we find H2O: ice, water, and steam.” Yet when we really think through such illustrations, they seldom help and often they make matters worse. In despair, and perhaps encouraged by the fact that the Bible never mentions the Trinity as such, Christians can be tempted to ignore this doctrine. If we would be Christians, however, we must resist this temptation, for the doctrine of the Trinity is indispensable to the faith “once for all delivered to the saints” (Jude 3).

Matthew’s final words emphasize just how indispensable trinitarian faith is, since baptism is the Christian initiatory rite, marking an individual’s inclusion in God’s new covenant people. In baptism, God puts his name on his children. So our Lord’s command that believers be baptized into the threefold name of Father, Son, and Holy Spirit tells us a lot about our God. As John Murray has observed, the fact that this is one name “indicates that all three persons [of the Trinity] conjointly claim our devotion in the distinguishing relations each person sustains to us in the economy of salvation.”

Furthermore, the benediction found at the end of Second Corinthians invokes a threefold blessing for grace and love and fellowship, with each blessing explicitly linked to one person of the Trinity. In other words, in the economy of salvation the grace that Christians receive is especially linked to the work of Jesus Christ, while the love that commissioned that work is especially associated with God the Father, and the fellowship we now enjoy with God and other Christians is especially tied to the Holy Spirit’s life in our hearts. Thus each person of the Trinity has a particular place in our “great salvation” (Heb. 2:1-4).

These passages help us to begin to realize why we need to understand and embrace the doctrine of the Trinity, for understanding and embracing it is essential for seeing and celebrating the glorious richness of our faith. Here we shall focus on the roles that Father, Son, and Spirit play in our salvation, which only allows us to begin plumbing the depths of these riches.

The Persons and Work of the TrinityGod’s Personality in the Old Testament

As Michael Horton’s article makes clear, the most basic biblical declaration about God is that he is “one.” The God who delivered his covenant people out of Egyptian bondage is not like the many Canaanite gods. His oneness implies that he is without beginning (see Ps. 90:2) and does not change (see Mal. 3:6; James 1:17). He simply is (see Exod. 3:14). These things cannot be said of the many gods of the pagan nations. And, of course, the New Testament writers echo repeatedly the theme of God’s unity (see Mark 12:29; Rom. 3:30; James 2:19, etc.).

Yet equally basic to the biblical understanding of God is the teaching that the God who is one is personal. To say that God is personal means that he is not a mere force but an active agent who hears us and relates to us (see Deut. 26:7-9; Ps. 34:17). He is a God who knows himself and us (see Jer. 29:11; Exod. 3:7). Because God is personal, he not only acts but he speaks. He spoke all reality into existence (see Gen. 1:3); he spoke with Moses “face to face” (Exod. 33:11); and he still speaks (see Heb. 1:2-3; 12:24-25).

God’s personality emerges immediately in Scripture at Genesis 1:26. The use of the first person plural in this verse-“Let us make man in our image, after our likeness”-does not prove the doctrine of the Trinity, but it at least represents God as interacting personally with someone. Furthermore, when in Genesis 11 Scripture records humanity’s attempt to build a ziggurat and climb up to God, it is not merely the human beings who are recorded as saying, “Come, let us build ourselves a city and a tower … and let us make a name for ourselves” (v. 4). In response, God says, “Come, let us go down and there confuse their language” (v. 7). In both of these verses, the plural language is most naturally read as referring to multiple persons. So at the very least it represents God interacting personally with someone and it may represent personal distinctions within God himself.

The Old Testament contains even stronger indications that God is not only personal but multi-personal, with the different persons having distinctive roles in creation and redemption. For instance, the Holy Spirit’s distinctive nurturing role is hinted at in Genesis’ first verses. Genesis 1:1 declares that God-in the Hebrew, Elohim-created the heavens and the earth. Yet in the second verse another agent is introduced, also with creative power: “The earth was without form and void, and darkness was over the face of the deep. And the Spirit of God”-the ruach of Elohim, in the Hebrew; that is, Elohim’s spirit or wind or breath-“was hovering over the face of the waters.” This introduction of God’s “Spirit” is not just vivid imagery, nor is God’s “Spirit” merely a synonym for “God,” because this verse elaborates how Elohim was creating-namely, by his Spirit “hovering” or “brooding” over the face of the waters (cf. Deut. 32:6, 10-11 which pictures God as creating and nurturing his covenant people by “fluttering over”-the Hebrew word is the same as “hovering over” in Gen. 1:2-them like an eagle with its young).

Some passages in the Pentateuch use the word “spirit” as a psychological expression (see Exod. 6:9; Deut. 2:30). So a passage like Exodus 31:3 could have said that God had filled Bezalel with his-that is, God’s-spirit. But it does not. Instead, it says, “I”-that is, the Lord, meaning Yahweh-“have filled him with the Spirit of God,” thus discriminating between himself and the Spirit, and thus suggesting that this Spirit is a distinct divine person who at the same time possesses all of Yahweh Elohim’s wisdom and authority and power (see also Num. 24:1-13).

Again, when Abraham is about to sacrifice his only son in Genesis 22, the “angel of the Lord” intervenes to issue a stay of execution for Isaac. But since it is God who is testing Abraham (see v. 1), only God can stop the testing. The fact that the angel says that he knows Abraham fears God because Abraham has not withheld his son “from me”-that is, from the angel of the Lord-confirms that the angel is a divine person rather than a creature. Indeed, the text makes the angel’s identity even more explicit in verses 16 and 17, when the angel calls out to Abraham from heaven for a second time, saying, “By myself I have sworn, declares the Lord, because you have done this and have not withheld your son, your only son, I will surely bless you, and I will surely multiply your offspring as the stars of heaven and as the sand that is on the seashore.” As Horton shows in his article, this angel of the Lord appears in several other biblical accounts, where he is consistently portrayed as a divine speaker and actor who is recognized as such (see, e.g., Exod. 3; Judg. 6:11-24).

Yet perhaps one passage, more than any other in the Hebrew Scriptures, reveals God in eternal, interpersonal communion with himself. Psalm 110 gives us a glimpse of two divine persons-Yahweh (“the Lord”), the God of creation and covenant, and Adon (“my Lord,” that is, master)-in personal interrelation. “Adon” in the Old Testament often refers to earthly masters but it is also used to refer to God himself, in combination with or as a synonym for Yahweh (see Exod. 23:17; Deut. 10:17; and Josh. 3:11). In this coronation drama, Yahweh invites Adon to take the heavenly throne with him, “Sit at my right hand.” Yahweh assures Prince Adon that he will conquer Prince Adon’s enemies and extend his kingdom (see vv. 1-2, 5-6). He also swears an oath to his Prince that he will be a priest forever after the order of Melchizedek (see v. 4 and Gen. 14:17-20). Originally, this psalm may have been composed to celebrate King David’s capture of Jerusalem and his subsequent accession to the Jebusite throne (see 2 Sam. 5:6-9). In any case, as Old Testament commentator Leslie Allen notes, the “great assurances of [this] psalm fell deep into the well of time till they finally plunged into the waters of [New Testament] revelation,” when our Lord and the apostolic writers used them to argue that David’s greater Son had appeared, who is indeed the second divine person of the holy Trinity (see Mark 12:35-37; 14:62 with Dan. 7:3; Acts 2:34-35; Eph. 1:20; Heb. 1:1-13; 5:6, 10; 6:17-7:28).

God’s Tri-Personal Work According to the New Testament

As the New Testament’s use of Psalm 110 makes clear, what was implicit throughout the Abrahamic, Mosaic, and Davidic epochs of redemptive history becomes explicit in the Scriptures of the new covenant. As the accomplishment of redemption through Christ’s earthly work drew near and then was historically fulfilled, God-through the words of his Son and the inspiration of his Spirit to Christ’s apostles-revealed each divine person’s role in the economy of salvation more clearly.

Here the passages from Matthew and Second Corinthians are central. When our Lord commands us, through commanding the apostles, to “make disciples of all nations, baptizing them in the name of the Father and of the Son and the Holy Spirit” and teaching them to observe all that he has commanded, this certainly includes teaching them the full truth about the Trinity.

This includes teaching them not only that there are three distinct persons in the Godhead, but also what part each person plays in our salvation, as Paul’s benediction suggests. The grammatical construction of that benediction in its original Greek links each of its blessings-grace, love, and fellowship-to a particular person of the Godhead by what is known as a “genitive of source.” Thus Paul is saying that the grace of God comes to us especially from Jesus Christ, the love of God particularly from God the Father, and the fellowship-or communion-that we now experience with God and other Christians especially from the Holy Spirit. But what exactly does that mean? And how should it affect Christian thought and worship?

It means that each member of the Godhead, even though each is fully God and equally to be worshiped, deserves particular recognition and praise for some particular aspect of our salvation. So when Paul links the blessing of God’s grace particularly to our Lord Jesus Christ, he is thinking about how Messiah Jesus, because he is both God (see John 1:1, 18; Rom. 9:5; 2 Pet. 1:1) and man (see Acts 2:22; Rom. 5:15, 17; 1 Cor. 15:21), could and did serve as the one mediator between God and human beings (see 1 Tim. 2:5). As God incarnate, he alone of the three members of the Godhead could and did meet the requirements of God’s righteous law for us as the second or “last Adam” (see 1 Cor. 15:45-49 with Rom. 5:12-19), quenching God’s wrath against us by paying the penalty for our sin by dying in our place (see Rom. 3:25-26; 1 John 2:2), and then being raised by God as both Lord and Christ to save all who believe (see Acts 2:22-36; 16:31; 1 Tim. 1:16). Through faith in what he has done, we can receive the forgiveness of our sins and the gift of God’s indwelling Holy Spirit (see Acts 2:38), which is the great blessing of the new covenant (see Ezek. 36:24-27 with Jer. 31:31-34, Gal. 3:1-14, and Heb. 7:11-13).

Likewise, when Paul links the blessing of love particularly to God-meaning God the Father, since Paul generally refers to the Father simply as “God” (see Rom. 1:1-9; 5:10; 1 Cor. 1:9)-he is in effect countering an error that some fall into even today. Sometimes Christians assume that our salvation comes almost exclusively from Jesus, as if a loving Son had to plead with his angry Father on our behalf. But this would imply a division of wills in the Godhead, which is profoundly unscriptural (see Matt. 26:39, 42; John 4:34; 5:30; Heb. 10:5-10). Indeed, the wills of God the Father and God the Son are so consonant that Jesus declared that “the Father is in me and I am in the Father” (John 10:38). Consequently, it is vital that we see that God the Father sent God the Son to be our Savior (see Gal. 4:4; 1 John 4:9-10) and that he has done this because he chose us “in Christ” before the world’s creation (see Eph. 1:3-6). It is the Father’s eternal love for his chosen ones that accounts for Christ’s appearing in history to accomplish the work of salvation (see John 3:16; Rom. 8:28-29). God the Father plans, purposes, and commands (see Luke 4:43; Acts 2:23; Eph. 1:9-10; 3:9-12); God the Son obeys (see John 6:38; 14:31; 15:10; Heb. 10:5-10). God the Father wills to save human beings through their faith in his Son (see John 6:40).

Thus God the Father’s love is the ultimate source of the grace that God the Son brings. In this sense, God’s love precedes Christ’s grace. Yet it is by Christ’s death that we are reconciled with the Father (see Rom. 5:10; 2 Cor. 5:18-21), which is probably why, in delineating the three chief blessings of our salvation, Paul inverts the natural order between the Trinity’s first two persons, mentioning Christ and his work first.

Finally, Paul attributes the fellowship that we now experience with God and other Christians especially to God the Holy Spirit, who has been sent by the Father and the Son (see John 14:26 and 15:26 with 16:7) to apply the grace won by Christ to the hearts of those whom the Father loves and has chosen to believe (see 1 Thess. 1:4-5; 2 Thess. 2:13-14; Acts 13:48). The Holy Spirit accomplishes this by regenerating (see John 3:5-8), leading and sanctifying (see Rom. 8:13-16; 1 Pet. 1:2), interceding for (see Rom. 8:26-27), and empowering God’s elect to do God’s work (see Acts 1:8; 1 Cor. 12:4-11; Heb. 2:4). Indeed, given that the indwelling of God in his people in the person of his Holy Spirit is the great blessing of the new covenant that has been inaugurated with Christ’s blood, it is not too much to say, with Charles Hodge, that the “primary object of the death of Christ was the communication of the Holy Spirit.” It is his life within us that engenders this fellowship that we now enjoy.

In summary, we may say that it is God the Father who initiates salvation, God the Son who objectively accomplishes it, and God the Holy Spirit who subjectively applies or completes it. When it is read with these “economic” distinctions in mind, the New Testament is full of allusions to the glorious and indispensably trinitarian work of the Godhead in bringing salvation.

Thus it is no wonder that the earliest church fathers confessed Trinitarianism almost immediately and that their confession came to be crystallized in the great ecumenical creeds.

The Theological Necessity of the Trinity

It should now be clear that it is profoundly wrongheaded for Christians to think of God as just one person. The theological consequences of Unitarianism, whether it is clothed in evangelical biblicism (“we’re just following Scripture”) or in apologetics (“we must speak of God only as one to defend the faith”) are enormous. It mortally wounds true Christian faith. Even if we say that we believe that God is three persons but then still permit ourselves or other Christians to think or speak as if God is only unipersonal, we marginalize the doctrine of the Trinity in a way that makes it little more than a second blessing for the enlightened few.

This is not what our Lord or the Apostle Paul would have us do. They would have us teach and celebrate our trinitarian faith in all of its richness and glory. As Hodge says in concluding his comments on the apostle’s great benediction: “The distinct personality and the divinity of the Son, the Father, and the Holy Spirit, to each of whom prayer is addressed, is here taken for granted. And therefore this passage is a clear recognition of the doctrine of the Trinity, which is the fundamental doctrine of Christianity.” For, as he continues, to be a Christian just is to be “one who seeks and enjoys the grace of the Lord Jesus, the love of God, and the communion of the Holy Ghost.”