What if christianity never existed ?

[abaris]

No it wasn't islam that killed off the classical world, considering that classical Europe's demise was two centuries prior to islam's founding. What you claimed is equivalent to me claiming tbat Socrates was executed because christianity demanded it.

Indeed. Tribal societies replaced the organised ones way before the rise of Islam. People often overlook that Northern Africa has been colonised by Goths and Vandals after the fall of the Roman empire. So, basically, and very roughly hitting the mark - germanic tribes during the migration of peoples.