Deuteronomy 20:18

18 that they not teach you to do after all their abominations, which they have done to their gods; so would you sin against the LORD 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 But of the cities of these peoples, that the LORD your God gives you for an inheritance, you shall save alive nothing that breathes;
17 but you shall utterly destroy them: the Hittite, and the Amori, the Kana`ani, and the Perizzi, the Hivvi, and the Yevusi; as the LORD your God has commanded you;
18 that they not teach you to do after all their abominations, which they have done to their gods; so would you sin against the LORD your God.
19 When you shall besiege a city a long time, in making war against it to take it, you shall not destroy the trees of it by wielding an ax against them; for you may eat of them, and you shall not cut them down; for is the tree of the field man, that it should be besieged of you?
20 Only the trees of which you know that they are not trees for food, you shall destroy and cut them down; and you shall build bulwarks against the city that makes war with you, until it fall.
The Hebrew Names Version is in the public domain.