Well, that is actually not really true - The KKK which often openly described themselves as being christian patriots really "enjoys" targeting churches only because the churchgoers were black or had "wrong" ideas about Christianity, like
https://en.m.wikipedia.org/wiki/16th_Street_Baptist_Church_bombing
https://en.m.wikipedia.org/wiki/Charleston_church_shooting
Sadly, sectarianism is still holding strong in practically every religion, I can sometimes even see this in Poland, where some of my catholic friends have really strange opinions about protestants or orthodox Christians. They are not at the point of murdering them, obviously, but still, they believe in the same God, so it is especially idiotic