They believe in the single personality of God, in contrast to the doctrine of the Trinity (three persons in one God ). It is the philosophy upon which the modern Unitarian movement was based and, according to its misled proponents, it is the original form of Christianity, while they don’t believe in Christianity (the doctrine from Christ/Christ-ianity), for they deny the fact that Jesus is the son of God – The Christ.
Unitarian Christians do not fully believe in the teachings of Jesus, as found in the New Testament and other early Christian writings, and hold him up as an exemplar.
Adhering to strict monotheism, the Unitarians maintain that Jesus was a great man and a prophet of God, perhaps even a supernatural being, but not God himself. Unitarians believe in the moral authority, but not necessarily the divinity, of Jesus. Their corrupted theology is thus directly opposing the Gospel and the theology of mainline Protestant and Orthodox Christian denominations which hold the Trinity doctrine as a core belief. It seemed the founder of Unitarianism decided that this was the best denomination type he could invent, silly as it seems.
Jesus never claimed to be God and neither is the Holy Ghost God: both are from God, and thus having authority men do not have.
“I and the Father are one.” The Jews took up stones again to stone Him. Jesus answered them, “I showed you many good works from the Father; for which of them are you stoning Me?” The Jews answered Him, “For a good work we do not stone You, but for blasphemy; and because You, being a man, make Yourself out to be God.”
And Jesus cried out and said, “He who believes in Me does not believe in Me, but in Him who sent Me. And he who beholds Me beholds the One who sent Me. I have come as light into the world, that everyone who believes in Me may not remain in darkness”.
JOH 10: 9 I am the door: by me if any man enter in, he shall be saved, and shall go in and out, and find pasture.
JOH 14: 6 Jesus saith unto him, I am the way, the truth, and the life: no man cometh unto the Father, but by me.
Here Jesus explains his authority, to us: virtually God. Not God, but ‘like God’. Only God could do the things he has done: no living man could.
So, the intelligent among us understand that, when Jesus makes this statement, he utters a proverb.