If a Christian commits a murder in self-defense is he still a murderer? In the Old Testament, they had a place called the cities of refuge, if I'm not mistaken. How about in this present time? What does the New Testament tell us? I need your insight on this.
The cities of refuge were places where an Israelite could flee to get a fair trial. If it was judged that a death was accidental, then the person was required to live in the city of refuge until the current High Priest died. Today, we refer to accidental deaths as manslaughter. "However, if he pushes him suddenly without enmity, or throws anything at him without lying in wait, or uses a stone, by which a man could die, throwing it at him without seeing him, so that he dies, while he was not his enemy or seeking his harm, then the congregation shall judge between the manslayer and the avenger of blood according to these judgments. So the congregation shall deliver the manslayer from the hand of the avenger of blood, and the congregation shall return him to the city of refuge where he had fled, and he shall remain there until the death of the high priest who was anointed with the holy oil" (Numbers 35:22-25).
Self-defense was considered neither murder (intentional) nor manslaughter (accidental). See Self-Defense and The Use of Force.