If Christ was entirely a created being, then the doctrine of the incarnation goes on the junkpile because there was nothing pre-birth to incarnate [take on flesh] as a man. He was created at conception as entirely a new form of sinless man, later indwelt by God's Spirit (which is why some here on TOL say He only BECAME the Christ only when the Spirit landed upon Him).
But what that must mean is that Christ had to be some unique one-only form of creation -- not a man nor an angel, but something else the Bible DOES NOT DEFINE.
What that means is, to deny the Trinity doctrine automatically puts your beliefs outside of what the Bible says and leaves you reliant on human speculations which cannot be supported by the word of God. In short...other people's opinions.
They define both God and Christ by human traditions.
Trinitarianism does its best to balance out everything the Bible says about the nature of Christ, and of God. Does it do it imperfectly? Probably, because we are imperfect. But at least it tries.
Antitrinitarianism (unitarianism, etc) has to ignore or rewrite entire chunks of the Bible to survive, as we've seen done on this very thread.