Deut.20.18

That they teach you not to do after all their abominations, which they have done unto their gods; so should ye sin against the LORD your God.

Deut.20.18

This is so there won't be any of them left to teach you to practice the abominations that they engage in with their gods and you end up sinning against GOD, your God.

Deut.20.18

Otherwise, they will teach you to follow all the detestable things they do in worshiping their gods, and you will sin against the LORD your God.

Deut.20.18

lest they teach you to do according to all their abominations which they have done for their gods, and you sin against the LORD your God.