Answer:

Nontrinitarianism is a theological view of God that rejects the doctrine of the Trinity. Any group that denies that God exists in three eternal, co-equal Persons sharing one nature in perfect unity is nontrinitarian. Within Christianity, broadly defined, are nontrinitarian groups that believe that God the Father is God but that Jesus and the Holy Spirit are not fully equal to Him.

There are several false ideas related to nontrinitarianism. There is adoptionism, which says that Jesus was “adopted” as the Son of God at some point during His earthly life—at His baptism, resurrection, or ascension, for example. There is also modalism, which asserts that God is an indivisible being who manifests Himself as one of three Persons at various times. Also, there is subordinationism, which says the Son and Holy Spirit are subordinate to the Father in nature and being. Nontrinitarian groups claiming the name of Christ include the Jehovah’s Witnesses, Mormons, Swedenborgians, Christadelphians, members of the United Church of God, and Oneness Pentecostals.

Nontrinitarianism is problematic because it is unbiblical and, at least in some forms, it makes Jesus Christ less than God. The deity of Christ is clearly supported by Scripture. Jesus said to the religious Jews, “I and the Father are one” (John 10:30). The Jews rightly took this to mean that Jesus was claiming equality with the Father. They replied, “You, a mere man, claim to be God!” (John 10:33). Then they tried to stone Him, which was the proper response to blasphemy, according to the law (Leviticus 24:16).

A nontrinitarian who believes that Jesus is not equal to the Father will have trouble explaining why the Jews were unjustified in their response. If you are not equal to God, it would be blasphemy to say you were. As God said, through the prophet Isaiah, He is the only God, and there is none like Him:

“I am God, and there is no other;
I am God, and there is none like me” (Isaiah 46:9).

In fact, if Jesus were not fully God, His statement to the Jews would have put Him on par with Lucifer, who in rebellion attempted to ascend to God’s throne (Isaiah 14:14).

The Holy Spirit is also God and yet distinct from the other Persons of the Godhead, according to the Bible. We see this in the story of Ananias and Sapphira, who “lied to God” (Acts 5:4). Peter also said that Ananias “lied to the Holy Spirit” (Acts 5:3). This was the same lie, from the lips of one man to one God. Lying to the Holy Spirit is thus equated with lying to the Father. The Bible also tells us that the Holy Spirit has distinct emotions, a distinct will, and a special purpose (Ephesians 4:30, 1 Corinthians 12:4–7; 2 Corinthians 13:14; John 14:25–26; 15:26–27; 16:7–15).

Why do nontrinitarian doctrines exist? What is the motivation to reject the Trinity? Part of the answer may be that the idea of the Trinity is so hard to grasp. How can the One God be also three distinct Persons? It makes no sense to our finite minds. But that is not a reason to discount it. There are many difficult doctrines that Christians struggle with, and many things in the Bible that seem impossible or are hard to understand. If we could fully understand everything God is and does, we would have a comfortable feeling of control. But, if anything, God’s mysterious and profound nature is an argument for the Bible being true. If there is a God who has the power to create us and the world around us, wouldn’t it make sense for Him to be beyond our understanding (see Isaiah 55:8)?

The clear and consistent teaching of the New Testament is that God exists in three Persons. Matthew 28:19 and 2 Corinthians 13:14 are two passages in which the doctrine of the Trinity is found. Jesus taught much about all three Persons of the Trinity in John chapters 14—17. And in His conversation with Nicodemus, Jesus speaks of the work of the Spirit who regenerates (John 3:8), the Son who was crucified (John 3:14–15), and the Father who sent the Son (John 3:16–17).

There is no doubt that the Trinity is difficult for human minds to grasp. We are not tri-personal beings; we are each one person. But God is unlike us. In His Word, He has revealed that He is of one nature and essence while at the same time eternally existing in three Persons. The Nicene Creed (AD 325) affirms that “we believe in one God the Father Almighty, . . . and in one Lord Jesus Christ, . . . and we believe in the Holy Spirit.”

The fourth-century Athanasian Creed did an admirable job in attempting to convey the truth of the triune nature of God, saying, in part,

“We worship one God in trinity and the Trinity in unity, neither confusing the persons nor dividing the divine being. For the Father is one person, the Son is another, and the Spirit is still another. But the deity of the Father, Son, and Holy Spirit is one, equal in glory, coeternal in majesty. What the Father is, the Son is, and so is the Holy Spirit. Uncreated is the Father; uncreated is the Son; uncreated is the Spirit. The Father is infinite; the Son is infinite; the Holy Spirit is infinite. Eternal is the Father; eternal is the Son; eternal is the Spirit: And yet there are not three eternal beings, but one who is eternal; as there are not three uncreated and unlimited beings, but one who is uncreated and unlimited. Almighty is the Father; almighty is the Son; almighty is the Spirit: And yet there are not three almighty beings, but one who is almighty. Thus the Father is God; the Son is God; the Holy Spirit is God: And yet there are not three gods, but one God. Thus the Father is Lord; the Son is Lord; the Holy Spirit is Lord: And yet there are not three lords, but one Lord. . . .

“And in this Trinity, no one is before or after, greater or less than the other; but all three persons are in themselves, coeternal and coequal; and so we must worship the Trinity in unity and the one God in three persons.”

Nontrinitarianism rejects these creeds and biblical teaching about the Trinity. Trinitarians affirm Jesus’ words in Matthew 28:19 concerning baptism “in the name of the Father and of the Son and of the Holy Spirit,” and they sing with conviction the words of the Doxology, “Praise Father, Son, and Holy Ghost.”