Since y'all brought up the question of Christianity, I wanted to throw in my $0.02.
I would suggest reading this. It lays out a solid response from on respected Christian minister to another on the topic of Christian and self-defense.
http://www.aomin.org/aoblog/index.php?itemid=2748Also, I'm not sure which one of you said it, but indeed, in the original hebrew the commandment, "Thou shalt not kill" is actually correctly translated, "Thou shalt not murder."
Now, here's something that an astute atheist doubter and others wanting to twist the bible for their own means may pull, and say that the meaning of the hebrew word translated "murder" actually means "to kill." This is correct, EXCEPT that every text has a context, and the context in which this word is used forces it to its secondary meaning of "to murder."
This is why all modern, accurate translations of the bible render that commandment to "Do not murder" instead of the King James Version's "Thou shalt not kill."
Also, someone may cite Matthew 5:39, and say that a Christian has no right to retaliate against any kind of evil. Once again, this comes out of ignorance of context. The context here (being slapped on the cheek) is in reference to personal insults. It has nothing to do saying that a Christian should not defend himself or his family against violent attack.
Some things to chew on for the believer who feels that he has no biblical warrant to defend himself. Indeed, the Christian should be concerned about the taking of another life, but not so much that he fails in his God-given duty to protect his loved ones.