Some people believe that God doesn’t manifest Himself in the form of God the Father, the Son, and the Holy Ghost. They believe that these are only roles He’s played throughout history. I’ve had experience with the United Pentecostal Church, the main proponent of the “Jesus only” doctrine, and I know they believe that everyone else is praying to a three-God system. By the process of elimination, the UPC also believes it is the one, true way. I don’t know of any church that teaches that the Trinity is comprised of three separate Gods.
The truth of the matter is, Scripture is full of examples of the multiple manifestations of God. For example, Matthew 3:16-17 says, “And Jesus, when he was baptized, went up straightway out of the water: and, lo, the heavens were opened unto him, and he saw the Spirit of God descending like a dove, and lighting upon him: And lo a voice from heaven, saying, This is my beloved Son, in whom I am well pleased.” Genesis 1:26 states, “And God said, Let us make man in our image, after our likeness…” And in 1 Peter 3:22, we read, “Who (speaking of Jesus) is gone into heaven, and is on the right hand of God; angels and authorities and powers being made subject unto him.”