That's a strictly cultural phenomenon, and it occurs throughout Africa (including Egypt) whether it's practitioners are Moslem, animist or Christian!
Islam per se, doesn't have a position on "beheading" infidels.
There are also plenty of Islamics that have not beheaded any infidels... some Islamic nations don't do it at all anymore... so tis not a specifically islamic function. Some leaders have come out and said this is "against Islam."
Besides, other cultures have done it, the french, the english and other European nations... so don't pin that ugly beheading last week on the religions of peacers so directly... /s
Your defense of the religion of peacers who regularly mutilate women as part of the process of "keeping them morally pure" is weak. Sell it to somebody else.