It is often said in the Bible that God spake unto Moses, but...

It is often said in the Bible that God spake unto Moses, but how do you know that God spake unto Moses? Because, you will say, the Bible says so. The Koran says, that God spake unto Mahomet, do you believe that too? No. Why not? Because, you will say, you do not believe it; and so because you do, and because you don't is all the reason you can give for believing or disbelieving except that you will say that Mahomet was an impostor. And how do you know Moses was not an impostor?