Death Penalty for Sex?

From verses 10 to 17 of Leviticus 20, we see God calling for the death penalty for atleast five types of sexual sins. It seems like God is quite serious about our sex lives. But why? Why does God care so much about the "with who, when, what, where and how" a person has sex?

For the atheist sexual rules are petty. But the atheist is ignorant. Imagine for a moment what the world would look like if sexual behavior was left unbridled? The Bible says deviant sexual behavior starts with atheism. Unfortunately, atheism is the primary school of thought that educates our kids at school. Therefore don't be surprised if the younger generation starts to become more sexually deviant.  

To the Godly, sex is powerful, good and a huge blessing. God made it and there is no shame in it. It should be respected. But it should also be enjoyed.