I think the mistake that's being made is that those practices were actually established in Paganism which of course it can actually be proved with many of them that they weren't. Or at least presumed. For example true Islam is considered as coming directly from Adam through the prophets - Abraham etc etc. Many of the practices that are assumed as Pagan in that article were practised by the prophets who Islam claims as it's own and by the people who lived it. For example fasting on certain days, Circumambulation (jericho?) and many other things.
Another thing I'd like to say is that Islam obviously has some of the same practices of Paganism - Paganism is simply a way in which humans live. Muhammad never claimed their entire life was wrong, just WHAT and WHO they worshipped, as far as I understand it. I apologise for anything that I say that is wrong! I'm a bit of a dunce sometimes.
at 9:38 AM on May. 8, 2011