Christian teaching about agape includes the belief that love should be shown unconditionally to everyone so it is difficult for many Christians to see how loving someone could involve killing them in a war.
The verse in Micah, “…Nation will not take up sword against nation…”, may be interpreted as meaning that peace is a feature of the kingdom of God and so therefore Christians should be peaceful themselves.
Much of the New Testament is about agape and peace and some may say that this is because Jesus had not come in the Old Testament (which suggests war and violence) and Jesus showed the nature of God much more clearly.
Several verses such as; “Love your enemies, and pray for those who persecute you.”(Matthew 5:44) and “If someone strikes you on the right cheek, turn to him the other also.” (Matthew 5:39). This may support the view that violence is never acceptable and Jesus is teaching that the right response to aggression is love, and Christians should not behave violently even when they are attacked.
Most Christians may also try to follow the example of Jesus. They may demonstrate this by behaving in the same way that Jesus behaved, may say that due to the way Jesus reacted at his arrest and the fact that he would not allow people to use violence to defend him, so therefore violence is wrong and peaceful methods of defence should always be used. “…for all who draw the sword will die by the sword.”
The 10 Commandments may be referred to i.e. “You shall not murder” reinforcing the point that killing people is never right in any circumstances.
The sanctity of life teaching; “man is made in the image of God” suggests that killing in a war might be wrong, because it involves taking a life away that has been made and planned by God.
In Isaiah 9, it talks of the “Prince of Peace” (Jesus) and is a message of peace referring to the coming of the Messiah so in this way people should prepare for the coming of the Messiah in a peaceful way.
These biblical teachings all confirm that it is never right to retaliate or to use violence even when others are aggressive, supporting pacifism.