God makes me holy, so I should keep God's decrees and follow them

Leviticus 20:1-27
Sacrificing his children to Molek, he has defiled my sanctuary and profaned my holy name.
A man or woman who is a medium or spiritist among you must be put to death.
Keep my decrees and follow them. I am the Lord, who makes you holy.
V 6-21: list the penalties for disobedience to laws in chapter 18 and 19.
That such a wide range of offences should be punishable by death seems incredibly harsh to the modern reader. (Where we remove wrongdoers from the community by putting them in prison, these laws remove them by death: a kind of moral/judicial surgery.)
All-it is worth nothing - are in deliberate defiance (蔑視) of God's holy law, or offences against people; none relate to property.
How?
For the custom in Canaan were worse and human personality are bed so the Lord made judicial surgery to cut off all wrongdoer and let people fear the law.
A man with clean heart and righteous behavior keep society or community clean and peace. Love make society has joy.
How?
Keep God's decrees and follow them, for He is the Lord, He makes me holy.