He is my God, do not defile the land where I am living

Leviticus 18:1-30
I am the Lord your God. Do not follow any of the detestable customs that were practiced before you came and do not defile yourselvess with them. If your defile the land, it will vomit you out as it vomited out the nations that were before.
There are many unlawful sexual relations have been done in Canaan.
Do not lie with a man as one lies with a woman; that is detestable.
Keep my decrees and laws, for the man who obeys them will live by them.
From what we know of Canaanite and Egyptian religions it is clear that many of these laws are directed against the specific practices of Israel's neighbours.
Marriage between those closely related by blood or by marriage is forbidden in Israel. In Egypt, which had no marriage-laws, such marriages were common.
Adultery, child-sacrifice, homosexual relations, bestiality were all pat of the indescribably debased religions of Canaan. Israel is to shun behaviour which is bringing God's judgment on the land.
V18 Jacob had done just this, and it led to great unhappiness.
V22 Among the ancient Egyptians and Canaanites sexual activity was almost deified: cultic(邪教) prostitutes were called 'holy ones' and homosexual practice and female prostitution were bound up with religious worship.
Why?
Fear the angry of the Lord, honor God's name, appreciate his salvation so we must obey his decrees and laws. It is good to us, we may live by them.
How?
He is the Lord, He is my God, do not defile the land where I am living.