He takes the "holy" Koran seriously. As long as the filthy Koran exists, Islam CANNOT be reformed and will continue to be a grave threat to human civilization.
That's the problem. It's pure hatred for Jews and Christians in that book --- yet we're allowing it while banning other hate speech. This killer and all the rest are just following the commands given to them in that book. Commands issued down from Mohammad who practiced what he preached and murdered many Jews and Christians himself.