Conversations with an angel

Reading NRO book reviews and The Truth About Muhammad-Founder of the World's Most Intolerant Religion by Robert Spencer is reviewed by Andrew McCarthy. I think I might buy it since I read Spencer's blog from time to time and he seems very scholarly in his discussions. No emotion but researched fact is more in line with his comments. Anyhow, as I read the review he talked about Spencer discussing all of Muhammad's life and it seems that Muhammad claims to have taken dictation from an angel and the words he wrote are directly from Allah. Now I may be wrong but didn't the founder of the Mormons also claim to have had direct conversation with an angel, Moroni or something of that sort? Abraham as well had angelic conversations and Mary did too. So whose angel should be the right angel? Maybe the research and arguments should begin there....