What's your point about Christianity having a commandment against killing and Islam not? Followers of Christianity kill in the name of religion to this day. They don't seem to take notice to the commandment.
What specific contemporary events of Christians killing in the name of religion are you referring to? Actually from the original Hebrew, the commandment is against murder, not killing. The Christian commandment is "Thou shalt not murder." "Thou shalt not kill" is an inaccurate translation. This is the response to give to all of those left-wingers who claim it is hypocritical to be against abortion but for the death penalty. Killing is sometimes justified in Christianity. Murdering innocent people (fetuses or 3000 office workers in the WTC, for example) is not.
Whereas in Islam the commandment is "Kill all infidels." There definitely is a big difference.
By in the name of religion I meant that there are supposed Christian people that kill others because of their religion. Just take a look at Northern Ireland.