That's not a function of religion, but a function of lust for power. People who want control over others will misuse whatever tool is handy to do it. When Christianity is most powerful, the powermongers will use (or misuse) Christianity. When Marxism is power, they will use that.
If there were no religion, there would still be torture. There would just be other rationalizations for it.
At least they would not be giving the Higher Being a bad reputation.