> Because that's old testament morals that have been deprecated by Christ.
In general, you're not wrong. In this case, though, you are. Matthew 19:16-19 [1]:
> 16 And, behold, one came and said unto him, Good Master, what good thing shall I do, that I may have eternal life? 17 And he said unto him, Why callest thou me good? there is none good but one, that is, God: but if thou wilt enter into life, keep the commandments. 18 He saith unto him, Which? Jesus said, Thou shalt do no murder, Thou shalt not commit adultery, Thou shalt not steal, Thou shalt not bear false witness, 19 Honour thy father and thy mother: and, Thou shalt love thy neighbour as thyself.
Had Christ intended to modify the commandment to "thou shalt not kill", I expect He would have.
[1] http://biblehub.com/kjv/matthew/19.htm