Shirk is the Islamic concept of the sin of polytheism specifically, but in a more general way refers to worshipping other than Allah, associating partners with him, giving his characteristics to other than him, or not believing in his characteristics. Within Islam, shirk isn't a forgivable sin, and Moslems consider that anyone who dies subject to this sin with it'll never see paradise. It is the vice that's opposed to the virtue of tawhid, literally "declaring [thatwhich is] one", often transla… (More on Mushrik)