Let's agree to disagree. But there is the following problem.

Personally, I think that claiming a new revelation is one of the ways you step over the line. I haven't thought much about it and could be wrong, but according to your "dangerous" line of thought, one could argue that Muslims are Christians. After all, the prophet Mohammed accepted the Bible as the word of God just like the prophet Joseph Smith did, and Muslims claim, I believe, just as the Jews do, that they worship the same God as Christians do. The Unitarians are Christians, so Muslims are not disqualified for rejecting the Trinity. I don't know this for a fact (and don't have time to check Wikipedia because I have to go out), but it seems to me that since the Unitarians reject the Trinity, they must reject the divinity of Christ, too. That means, so far as I can see, that according to your line of thought, if the Unitarians are Christians, then so are the Muslims.

Gnostics didn't claim they had new revelation. They had their own gospels that were written at about the same time as the canonical ones.

A bomb, H bomb, Minuteman / The names get more attractive / The decisions are made by NATO / The press call it British opinion -- The Three Johns