But the muslims are doing it for allah.
Islamist kill for their false god, Communists kill for “the revolution.” I don’t see much of a difference. It is a pattern seen throughout history.
Christianity is somewhat unique in that, while many people have killed in its name, Wars of the Reformation, the Conquistadores, etc... They were often condemned by other Christians at the time and generally have been condemned by subsequent generations. We recognize our inherently sinful nature and try hold ourselves to a higher standard.
Sadly, you can easily find Communists and Islamists who look to the past for “how to” tips instead of contemplating the sins of previous generations.