You're telling me that in 80 years, Communists managed to kill more people than thousands of years of jihads, crusades, wars, skirmishes, sacrifices and persecutions?
Dont bet the farm on it but I almost positive I have seen statistics that show that to be true.
Can't speak for Islam, but the number of souls killed by the various agents of Christendom is a FRACTION of what Stalin himself accomplished in a single decade.