(And if we were to count the number of non-Christians killed by Christian Roman Emperors claiming to be acting under the Christian God's mandate in the centuries of Rome's unraveling, well, there simply is no contest)
In islam, however, it divides the world into Dar al-islam (the House of islam) and Dar al-harb (the House of War, i.e infidels). Muslims are commanded by their allah in the quran and hadith to fight those who disbelieve and unbelieve; to behead and slaughter them wherever they find them UNTIL ALL RELIGION IS FOR ALLAH. That's a mandate for muslims to conduct a perpetual war against non-muslims simply for their unbelieve and disbelieve until they submit to islam. Even apostates have to be killed. That's islam.
"How do I know what I think 'till I hear what I say?"