And no believer can kill a believer except by mistake; and whoever kills a believer by mistake then he should free a believing slave and deliver good ransom to his family except they remit it freely. And if he is from an enemy people to you and he is a believer, then should free a believing slave, while if he is from a people with whom you have a treaty, then deliver a good ransom to his family and free a believing slave. Then if anyone is unable to free a slave, then he should fast for 2 months uninterruptedly, as repentance from Lord Allah; and Allah is the All-knowing, the Wise.
Today, as there is no a group of believers there’s no war and killing. Believer who considers the Lord as Impartial will not kill any soul except with Truth as told in verse 25: 68. Remember that without Adhikr none will become a believer. The burden of bloodshed, killing and all such mischievous activities happening anywhere in the world should be borne by the hypocritical men and women as well as the Mushrik men and women before the Impartial Lord. That is why they are denoted as the worst creatures among 1000 communities of creatures as told in verse 8: 22. They are following all satanic footsteps rejecting verses 2: 168-169. See the explanation 2: 5, 30 and 3: 183.