In some sense Zakir Naik has been defending and preaching some thing which he does not know completely. This is alright in itself. It is doubtful that one case make claim to knowing all of Deen before one takes to the podium. Islam's rule is to communicate even if you have a single Verse. That, I suppose, Zakir Naik is doing. Unlike many of us. I also have the feeling that by now he is aware of the fact that some areas of Deen are not within his easy reach. I hope he takes the best route henceforth.