Self defense may result in one of the greatest examples of human love.
John 15:13- Greater love has no one than this, that someone lays down his life for his friends.
Christians are unselfishly risking their life for the sake of others when they protect their family or neighbor.
To not engage in self defense or the defense of others is morally wrong. To allow murder to take place when one could have prevented it is immoral.
James 4:17- Not resisting evil is an evil of omission.
The basis for self-defense is similar to just war and selectivism. To not respond to a bully nation seeking to destroy or injure a less powerful nation or group of people is to fail morally.
In Acts 22: 25-29, Paul never says he thought it was wrong to engage in self defense when he appealed to Caesar. His life was in danger of being unjustly taken. He appealed using his Roman citizenship. He appealed to the military might and the protection of the Roman army.
The Bible defends the concept of self-defense.