"Christianity has always been high on the list of the most brutally cruel and vengeful religions" - absolutely not! In fact, one of Christianity's few express commands is "love your enemy". It can hardly be blamed if people - even its supposed followers - disobey its teachings.

I guess it depends on what you mean by "religion": this can mean several different things, which it's important not to confuse.
It can be a particular set of beliefs - e.g. Christianity, Judaism, Buddhism.
Or it can be such beliefs in general, as in "Comparative Religion".
Or, it can refer to a particular organisation professing and (supposedly) applying such beliefs, e.g. the RC Church or the Salvation Army.

These organisations are run by human beings, and are as much at the mercy of human failings as any other corporate body, however high their stated principles. Hence the sad situations where ordained ministers misbehave and their parent body, instead of disciplining them, covers up for them. Or different branches of the Church find themselves on opposite sides of a political problem, and stoke fires that they should be trying to extinguish.

Which doesn't excuse any of these evils, but putting the blame in the wrong place doesn't help.