It's not just about angels, but ANYONE that preaches another gospel.
Sure, and like I said, Mohammad didn't preach a gospel so can't be accused of preaching a wrong gospel.
Islam preaches a gospel that denies God has a Son, and that His Son was bodily resurrected.
That is in direct opposition of Christianity.
Actually, no, Islam does not deny he was resurrected. I used to think that before I looked into it more. One of a myriad of myths about Islam. Be that as it may, the Christian Gospel is not a doctrinal understanding about God or Jesus, it's the good news about the Kingdom of God having come to earth.
If that is what you believe, then you could just as easily chunk the entire bible.
So what do you even base your "Christianity" on?????
It's not based on someone's report of what angels said, it's based on an something more verifiable, such as an empty tomb, and the teaching of the one who rose from it. If that eliminates Paul's testimony, so be it. I don't need Paul to be a Christian, though he does provide some awesome truths about the New Covenant, walking in the Spirit, loving each other, etc. BTW, if you get a chance to witness to Muslims, forget about quoting anyone other than Jesus, but certainly do quote Jesus, since he is one of their prophets too.