Why do atheists think Christianity is as violent as Islam?

They love to point out these things yet are quick to distance themselves from the communist slaughters which were committed in a relatively short time span by comparison and numbered into the millions. And the communists were by no means religious if ya know what I mean. It is the extremists with there own agenda that like to portray Christianity in this light and I ure you there is a motivation. Only seven people died in abortion related violence unless of course you count the aborted.