The Israelites are told to destroy the places of worship of rival religions. This is because their existence is a temptation to idolatry, one to which many Hebrews would eventually give in. There is one God, separate from all other religious influences. Worship of the Lord is done in one central location set aside by Him: a special, sacred place. All sacrifice and offering to the Lord will not be done at local shrines, but at His chosen location. This will help prevent His worship from being diluted by local practices.