Andy: I think he only means to say that if you believe the truths of one monotheistic religion, you also believe that the other ones are false. That doesn’t necessarily mean that you don’t tolerate their followers, only that you believe them to be in error as to how they approach divine truth.

This exclusivity is a feature of Christianity and Judaism as well as Islam. There’s no such thing as a half-Christian, either. The difference is that Christian churches do not generally prescribe death for apostates — Christians who become Muslims, for example.