Because men didn't write the bible.
Oh, and let's stick to the truth of killing homosexuals
"If a man lies with a male as with a women, both of them shall be put to death for their abominable deed; they have forfeited their lives." (Leviticus 20:13 NAB)
also raping women
(Deuteronomy 22:28-29 NLT)
If a man is caught in the act of raping a young woman who is not engaged, he must pay fifty pieces of silver to her father. Then he must marry the young woman because he violated her, and he will never be allowed to divorce her.

????? GJ quoting old testament

So the Old Testament is no longer valid?

You have to remember, we are no longer under the Levitical priesthood. We have a new high-priest, his name is Jesus Christ.

Here's a good article on the civil/ceremonial/moral law of the OT. It's a tough question, but I think he handles it well here: (Plus the title is funny)
http://www.whitehorseinn.org/blog/2011/09/27/%e2%80%9cwhy-can%e2%80%99t-i-own-canadians%e2%80%9d-rightly-dividing-the-word-of-truth/