Are Christians biblically justified to use force for self-defense? Depending on the situation, the answer is sometimes yes, and sometimes no. Killing a thief is both justified and unjustified, depending on the situation (Ex 22:2-3). In Scripture there are examples of believers who at one time defended themselves or others, but then at other times fled and/or suffered for their faith. David, who killed Goliath (1 Sam 17:48-51), twice fled when Saul tried to kill him with a spear (1 Sam 18:11; 19:10), and refused to retaliate, even when he had opportunity (1 Sam 24:4-6).