The Trinity is monotheism

You may have strong reasons to distrust this doctrine. If you are a Muslim, the Qur’an tells Christians, “do not say, ‘Three’,” and it pictures Jesus being asked whether he told people to take him and his mother as deities besides God (Qur’an 4:171; 5:116). If you are Jewish, you may say the Shema, Israel’s confession that the LORD is one, every day, and the Trinity may sound like the very thing it forbids. If you are one of Jehovah’s Witnesses, the brochure Should You Believe in the Trinity? has taught you that the doctrine is a later idea with pagan roots.

Christians do not believe in three gods. They do not believe God took a wife and fathered a son. Mary is not part of the Godhead, and no church council ever taught that she was. Some popular objections, and some readings of verses such as Qur’an 5:116, target these ideas, and it helps to clear them away. That does not answer the objection itself. Classical Muslim commentators such as Ibn Kathir, writing on Qur’an 4:171 and 5:73, reject the Christian teaching that Jesus is divine and God’s Son as such, and Jewish tradition rejects it as well.

Nor is the Trinity one God who appears sometimes as Father, sometimes as Son, and sometimes as Spirit, like one actor wearing three masks. The early church rejected that view as well.

Stated positively, the Trinity is the Christian teaching that the one God exists eternally as three persons, Father, Son, and Holy Spirit, who share one divine nature.

The charge of contradiction assumes that “one” and “three” are said of the same thing. They are not. Christians say God is one in being, meaning what God is. They say God is three in person, meaning who God is. A person, in this older sense, is someone who can say “I” and be addressed as “you.” So the claim is one what and three whos.

That is hard to picture, and Christians say so. Nothing in our experience is quite like it. But a claim can be hard to picture without being a contradiction. “One being who is three persons” does not say one equals three in the same respect.

The word “Trinity” is not in the Bible, and the formal wording came later. The Council of Nicaea in AD 325 and the councils that followed set out the language of one being and three persons. Does that language describe what the Bible already says, or add something foreign to it? The sections below test that. As for pagan triads, groups of three gods existed in several ancient religions. They were three gods, which is exactly what the Trinity denies.

Christian belief about God is built on the Shema, not set against it. “Hear, O Israel: The LORD our God, the LORD is One” (Deuteronomy 6:4). Jesus himself called that the first commandment (Mark 12:29).

The first Christians were Jews, and they kept the Shema. Paul, a Pharisee by training, writes to Christians in Corinth, a city full of temples: “for us there is but one God, the Father, from whom all things came and for whom we exist. And there is but one Lord, Jesus Christ, through whom all things came and through whom we exist” (1 Corinthians 8:6).

Richard Bauckham, a New Testament scholar, points out that Paul has taken the two key words of the Shema, “God” and “Lord,” and arranged the one confession around both the Father and Jesus. He does not add a second god beside the first; that would break the Shema. He places Jesus inside it, as the one through whom all things came. If you do not accept Paul’s letters as Scripture, read this as evidence of how early Jewish followers of Jesus spoke about God.

The Father, the Son, and the Spirit are not three names for one person. They speak to and about one another. In John 17:5 the Son prays, “Father, glorify Me in Your presence with the glory I had with You before the world existed.” In John 14:26 Jesus says the Father will send the Spirit in the Son’s name. At Jesus’ baptism, the Son is in the water, the Spirit descends, and the Father speaks from heaven (Mark 1:10-11).

Yet the New Testament also gives each of them what belongs to the one God. All things were made through the Son (John 1:3), angels are told to worship him (Hebrews 1:6), and Thomas calls him “My Lord and my God!” (John 20:28); the evidence is set out in Jesus is God. Lying to the Holy Spirit is called lying to God (Acts 5:3-4), and the Spirit acts with a mind and will of his own, as shown in the Holy Spirit is a person.

Jesus gathers all three under one name: baptize “in the name of the Father and of the Son and of the Holy Spirit” (Matthew 28:19).

Larry Hurtado, a historian of early Christianity at the University of Edinburgh, showed that Jewish followers of Jesus were worshiping him alongside the Father very early, while still insisting there is one God. The later doctrine was written to explain that worship, not to invent it.

Shirk, in Islam, is associating partners with God. Jewish law forbids avodah zarah, foreign worship. Christians agree that both are wrong. A Muslim or Jewish reader can understand everything above, including that “begotten” means an eternal relationship and not a physical birth, and still judge that a Son and Spirit within God are incompatible with his oneness. Islam rejects divine sonship in that eternal sense too. That is a real disagreement, not a misunderstanding.

Christians answer that a partner is someone other than God who shares what is God’s, and that oneness rules this out completely. The Son and the Spirit, they say, are God’s own Word and Spirit, sharing his one being, and not other beings beside him. The Qur’an itself calls Jesus God’s “word” and “a soul [created at a command] from Him” (4:171); Muslim interpreters read that as created, and Christians read it as pointing to the eternal Word. Whether oneness rules out every distinction within God, and whether Jesus is that Word, are the two questions that divide these faiths.

The Trinity claims one God, with no partner and no creature worshiped. This page does not show that the claim is coherent to every reader or that the doctrine is true. That depends on whether the earliest sources about Jesus are reliable and on what they say about him, which is why the next questions are historical ones, taken up in the reliability of the New Testament.