Wait, that's the same questions we ask of you about the Bible...all you've ever said is that it's written by in the Bible by so-and-so who had witnesses that we only know of from the that writer...you're merely making assertions and claim they are true...no different...
I believe this is why Jesus went first to the Jews. It established HIS legitamacy.
Jesus amazed everyone in HIS knowlegde of Scripture even though HE had not been schooled. Jesus could read and write but HE lacked the formal, scribal training. HE had never studied under a trained, recognized rabbi or sage.
14 Not until halfway through the festival did Jesus go up to the temple courts and begin to teach. 15 The Jews there were amazed and asked, “How did this man get such learning without having been taught?”
16 Jesus answered, “My teaching is not my own. It comes from the one who sent me. 17 Anyone who chooses to do the will of God will find out whether my teaching comes from God or whether I speak on my own.
Mohammad had no miracles or signs from GOD. He did not fulfill prophecy. He had no eyewitnesses to what was being revealed. Mohammad gave us nothing new of theology. What was given was a bit lacking or twisted.
Mohammad was preaching to pagans and idolitors who could question nothing. Poor man did not even understand the Holy Spirit and gifts of the Spirit.
Unless the understanding/interpretation of the Quran has been lost over the years. I sort of go between thinking Islam, the Quran and Mohammad are completely false and it has simply been interpreted wrong. So much of the Quran is vaque either is a possibility.
Interesting article, this Muslim doesn't even think Mohammad existed! I beliseve he did but was he a prophet or simply a poet?:
Professor Hired for Outreach to Muslims Delivers a Jolt
Islamic Theologian's Theory: It's Likely the Prophet Muhammad Never Existed.
He traded ideas with some scholars in Saarbrücken who in recent years have been pushing the idea of Muhammad's nonexistence. They claim that "Muhammad" wasn't the name of a person but a title, and that Islam began as a Christian heresy.
Prof. Kalisch didn't buy all of this. Contributing last year to a book on Islam, he weighed the odds and called Muhammad's existence "more probable than not." By early this year, though, his thinking had shifted. "The more I read, the historical person at the root of the whole thing became more and more improbable," he says.