Deuteronomy 20:18

18 so that they won't teach you to follow their abominable practices, which they do for their gods, thus causing you to sin against ADONAI your God.

Deuteronomy 20:18 Meaning and Commentary

Deuteronomy 20:18

That they teach you not to do after all their abominations,
&c.] This is another reason why they were to be utterly destroyed, not only because of the abominations which they committed, but to prevent the Israelites being taught by them to do the same; wherefore, as before observed from Jarchi, such as became proselytes were suffered to live among them, because there was no danger of idolatry from them, which even proselytes of the gate renounced; and though all other abominations are included, yet this is particularly respected, as appears from the following clause:

which they have done unto their gods;
to the honour of whom not only many superstitious rites and ceremonies were performed, and idolatrous actions committed, but acts of lewdness, and even unnatural uncleanness:

so should ye sin against the Lord your God;
a sin the most provoking to him, as the sin of idolatry was; and cause his anger to rise to such a degree, as to suffer them to be carried captive from the land he gave them to inherit; and which afterwards, was the case, and that through learning the manners and customs of these people; see ( Psalms 106:34-42 ) .

Deuteronomy 20:18 In-Context

16 "As for the towns of these peoples, which ADONAI your God is giving you as your inheritance, you are not to allow anything that breathes to live.
17 Rather you must destroy them completely - the Hitti, the Emori, the Kena'ani, the P'rizi, the Hivi and the Y'vusi - as ADONAI your God has ordered you;
18 so that they won't teach you to follow their abominable practices, which they do for their gods, thus causing you to sin against ADONAI your God.
19 "When, in making war against a town in order to capture it, you lay siege to it for a long time, you are not to destroy its trees, cutting them down with an axe. You can eat their fruit, so don't cut them down. After all, are the trees in the field human beings, so that you have to besiege them too?
20 However, if you know that certain trees provide no food, you may destroy them and cut them down, in order to build siege-works against the town making war with you, until it falls.
Complete Jewish Bible Copyright 1998 by David H. Stern. Published by Jewish New Testament Publications, Inc. All rights reserved. Used by permission.