The first thing to keep in mind is that The Bible as we know it today is incompatible for one important reason. We have 66 separate books that are treated as one complete "novel". In reality these books were never written with the intent of compiling them into one complete "story". In most cases the writer(s) of a given text never read, referred to, or even heard of the other texts. The numerous discrepancies we find between texts is largely due to this fact in addition to many others.

When we add the Koran into this confusion it only gets worse. While Islam would not exist without the Hebrew and Christian traditions, the very core of Islam was intended to be a reformation of what wasn't happening in those traditions. Much in the same way that Christianity was a critique of Judaism, Islam was a critique of both traditions. For this reason the similiarities between the traditions are definitely outweighed by the differences. Islam was a new way of thinking and being in relationship to Allah.