So would you say that people that do hateful things and justify that with Christianity aren’t Christians?
Generally speaking. I wouldn’t say that the Westboro Baptist Church are not Christians. They’re very extreme, but most of their shit (with the exception of the name-calling, which is condemned in the Bible) isn’t necessarily unbiblical. The thing is, violence is not permitted for Christians. The New Testament flat out says that it’s damning to even follow the laws of the Old Testament. It’s debatable to what extant self-defense is even permissible in Christianity. Violence is not prohibited in Islam (which I know is what you’re getting at).
EDIT: I forgot that the Westboro Baptist Church frequently puts themselves in the position of the arbiter between Heaven and Hell. They say specifically who is and isn’t going to hell, which is unbiblical.