IYO, were the members of the KKK, who justified their actions by referring to their Christian faith, "monsters" as well? I lived during the latter part of the era whereas they murdered people, but I don't recall any politician or any reporter referring to them as "Christian terrorists". Did you ever hear that?
We have to remember that people tend to justify their atrocities, and often religion was and still is used by various groups as an excuse. How much of it is just radical "politics" versus how much of it is true "religious" convictions I cannot say, but people throughout history often justified their atrocious behavior by citing select verses from the Bible, the Qur'an, etc. It's not right for them to cherry-pick to justify such atrocities, imo, but it happens-- unfortunately.