What is the punishment of a killer in Christianity?

Answer 1

The BBC provides a useful, concise summary of the Christian position, saying: "For much of history, the Christian Churches accepted that capital punishment was a necessary part of the mechanisms of society." Murder, attempted murder and manslaughter were only some of the reasons the death penalty was considered appropriate -- even heresy was included in the list.

In modern times, most countries with a Christian majority population determine punishments according to secular law, which now overrides religious law. The tendency is to move away from the more barbaric death sentence to lengthy prison sentences, with twenty years or life imprisonment quite common for premeditated murder. A useful advantage is that if, as occasionally happens, the accused is subsequently found not guilty, a prison sentence can be commuted.

Answer 2

There is not one stance on this issue. Some Christians believe that we should still follow Old Testament Law, which states: "Anyone who takes the life of a human being is to be put to death."
(Leviticus 24:17)

Others believe that we are no longer bound by the legal code of Old Testament Law. (Also, according to Old Testament Law, people were put to death for things like doing work on the Sabbath and making false statements about a woman's virginity.) Jesus never specifically spoke against capital punishment, but when the woman caught in adultery was about to be stoned to death, he said, "Let any one of you who is without sin be the first to throw a stone at her." (John 8:3-11)