I think to go about making your belief that Islam is more violent than other religions persuasive, you need to limit your analysis to scripture - because the moment you try to use actual events and behavior as evidence you'll end up having to contend with the crusades, the spanish inquisition, the KKK, and similar behavior. For what it's worth, I think if you limit your analysis to scripture you're on pretty solid ground for Islam vs. Christianity. Less solid for Islam vs. Judaism. But then what exactly is the takeaway from that conclusion? I'm not sure.
Given the history of Christian and Jewish violence, as well as violence from other religious belief, it seems that religion is just a bad idea altogether. Sure, Islam does not appear to be a good one, but it's definitely not the only one that's violent.