Deuteronomy 20:18

18 that they may not teach you to do all their abominations, which they did to their gods, and ye should sin before 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 ye shall not take any thing alive;

17 but ye shall surely curse them, the Chettite, and the Amorite, and the Chananite, and the Pherezite, and the Evite, and the Jebusite, and the Gergesite; as the Lord thy God commanded thee:

18 that they may not teach you to do all their abominations, which they did to their gods, and ye should sin before the Lord your God.

19 And if thou shouldest besiege a city many days to prevail against it by war to take it, thou shalt not destroy its trees, by applying an iron tool to them, but thou shalt eat of it, and shalt not cut it down: Is the tree that is in the field a man, to enter before thee into the work of the siege?

20 But the tree which thou knowest to be not fruit-bearing, this thou shalt destroy and cut down; and thou shalt construct a mound against the city, which makes war against thee, until it be delivered up.