You just told me "Neither should you", so you just judged. We all must judge, but the question is whether you're judging righteously, according to the NT Bible, the teachings of Jesus Christ and His apostles. Is your judgment in line with Biblical teaching? Nothing in the NT Bible says anything about Christians killing people who would do them harm. Just because someone could do you harm, doesn't give you the right to kill them. You should pray for them, that's Christ's teaching. Don't return evil for evil, harm for harm.