There is only one God
The Bible begins with one Creator, not a collection of competing gods. Israel was surrounded by nations who worshipped many deities, yet Moses called God’s people to worship the Lord alone. God later declared through Isaiah that no other God stands beside him or after him (Isaiah 45:5).
This matters because the one true God is not a local deity or a spiritual force among others. He made heaven and earth, knows his people, judges evil with righteousness, and keeps his promises. Scripture’s answer is clear: there is one God.
Hear, O Israel: The Lord our God is one Lord:
Jesus points us to the Father
On the night before his crucifixion, Jesus prayed to the Father and described him as the only true God. He also spoke of himself as the one the Father had sent, which means knowing God cannot be separated from receiving Jesus (John 17:3).
Jesus did not present a different god from the God of Israel. He came to make the Father known. Yet the New Testament also gives Jesus honour and descriptions that belong to God. John introduces Jesus, the Word, as existing in the beginning and as fully divine (John 1:1).
And this is life eternal, that they might know thee the only true God, and Jesus Christ, whom thou hast sent.
Father, Son, and Holy Spirit
Christians have long used the word Trinity to describe what Scripture shows. The word itself is not found in the Bible, but it is a helpful shorthand: God is one, and the Father, the Son, and the Holy Spirit are distinct from one another and fully involved in God’s saving work.
Jesus told his disciples to baptise in the single name of the Father, Son, and Holy Ghost (Matthew 28:19). Paul likewise speaks of one God, the Father, and one Lord, Jesus Christ, through whom all things exist (1 Corinthians 8:6). The Spirit is not treated as an impersonal influence either. Peter’s words to Ananias connect lying to the Holy Ghost with lying to God (Acts 5:3-4).
This is a mystery, but not a contradiction. Christians do not believe in three gods. They believe the one God has made himself known as Father, Son, and Holy Spirit.
Go ye therefore, and teach all nations, baptizing them in the name of the Father, and of the Son, and of the Holy Ghost:
Knowing the true God
The question is personal as well as theological. The true God is not known merely by getting the right definition. Jesus came so people could know the Father, trust the Son, and receive new life through him (John 17:3).
If you are exploring, begin with one of the Gospels and pay close attention to Jesus. Notice whom he prays to, what he says about his identity, and how he welcomes people. The Bible invites honest seeking. The God it reveals is one, living, holy, and near to those who turn to him.