Self defense is not a crime as long as the Bible is concerned. According to the book of Exodus 22 vs 2&3, if there happens to be a situation where a thief breaks into a home and the occupant in the house takes the thief's life, such person does not stand any penalty of the law.
Being christians does not debar us from protecting ourselves. Anybody is entitled to protection by any means they dim fit. There was never a place in the Bible that condemned self defense. Arranging for a means of protection is not an evil thing, on the contrary it is a wise action one should take.
If the deed is already done then it is a different case all together. But if it is something that is currently in motion and there's a way of defending oneself then there's no crime. Because we are christians doesn't give the unbelievers the license to slaughter us like chickens.
