I reckon it'll balance out eventually. You have to remember that Chrisitanity has been around for longer than Islam, with Muhammed dying in 632CE.
The Muslim religion did from its early days, embrace warface and Muhammed himself conducted a series of brutal campaigns while subjugating Mecca. Islam doctrine acheived a far more rapid and natural union of faith and violence than that concocted in the Latin West. By the late eighth century Muslim jurists had enshrined these ideals in a formal theory of holy war. The obligation to prosecute jihad, the military struggle against the infidel, was incumbent on all able-bodied Muslims, and would, it was believed, pave the way to paradise. By the eleventh century, though, these ideals had been turned towards internal conflicts between the Sunni's and the Shi'ites.
Chrisitanity has had its fair share of killing innocents, with the First Crusade being started by the Pope Urban II, who used a cry for help from Byzantine as a cover story to rouse Latin passions. He told people that all of their sins would be washed away if they were to take up arms and travel to the East to reclaim the Holy Lands.
There's so much evidence to throw into the mix, the Romans, the Nazi's, etc. that you could talk about it forever. However, being an etheist, I have to lean towards Islam having the bigger propensity for violence. One Muslim Turk lord captured some barbarians, and blinded 99 out of every 100, leaving one man left to show the others the way home!
Anyways, I'll just throw all that into th mix and see what happens!