Do not defile the land where I awe

Numbers 35:1-34
Giving Levites 48 towns include 6 cities of refuge. Each town have pastureland with 3000 feet on the north, south, east and west side.
Three cities of refuge on both side of Jordan.
Moses announced the rules of the city of refuge.
Do not pollute the land and atonement cannot be made for the land on which blood has been shed, except by the blood of the one who shed it.
Do not defile the land where you live and where I dwell, for I, the Lord, dwell among the Israelites.
Why?
Cities of refuge let the innocent murders safe their life.
The Lord like the righteousness, He do not like evils and sins. If there are sins and polluted the land, He won't dwell among them. The Lord is holy God.
The Lord is mercy so he asked Israelites make cities of refuge, let a person who has killed someone accidentally may flee.
How?
Mercy and Righteousness are not conflict, sin and atonement are need to be clarified. Don't defile the land where I am.