When I hear a person say that they are Christian, but then boast about how they would kill another person, because their target is a pedophile, cop killer, marauding Muslim, racist or any other kind of despicable human being, I realize they either have a head problem or a heart problem or both. Their thinking is wrong, because the New Testament is totally clear, concerning the fact that Christians do not kill other people for any reason, and their affections are warped, because they love vengeance more than redemption.
The New Testament directive to Christians concerning vengeance and violence is confusing to some people because they understand that God has established laws and justice to deal with evil doers. What they do not understand is that God gave the sword of law and order to the State (the power of the police, the courts and the military) to punish the wicked and protect the righteous, and He gave the sword of the Spirit (the Holy Bible) to believers to wage spiritual warfare against sin, while loving our enemy.
Very few preachers proclaim this truth, but it is the New Testament position. Don't be confused by false teachers and popular beliefs. Be a Bible Christian instead.