Charles Ellicott Commentary Deuteronomy 7:2

"and when Jehovah thy God shall deliver them up before thee, and thou shalt smite them; then thou shalt utterly destroy them: thou shalt make no covenant with them, nor show mercy unto them;" — Deuteronomy 7:2 (ASV)

And when the Lord thy God shall deliver them before thee... —It would be possible to read, “Then the Lord your God shall deliver them before you, and you shall smite.” Or the sentence might also be divided thus: “When the Lord your God shall bring you in, and shall have delivered the nations from before you, and you have smitten them, then you shall utterly destroy them”—that is, you shall make them chêrem, a devoted or accursed thing. Perhaps this last way of dividing the clauses is, on the whole, to be preferred. But in any case it should be noted that Jehovah’s deliverance of the nations into Israel’s hand is to precede their defeat and extermination.

Indiscriminate attack and massacre are not to be thought of. (For a further note on this, see Joshua 13:0.) All the operations described in Joshua—the sieges of Jericho and Ai, the southern campaign and the northern campaign—were alike undertaken under Divine direction. The same may be said of the battles in Moses’ lifetime, whether against Amalek, Sihon, Og, Arad, or Midian. The same is true of the judges, and of David’s operations against the Philistines after he came to the throne (2 Samuel 5:19 and following). The principle was acknowledged by Ahab in his attack on Ramoth-gilead (1 Kings 22:0).

Thou shalt make no covenant with them. —The reason for this is too obvious to need comment. If Israelites and idolaters were united—still more if they were intermingled in marriage—there was an end to the distinction of race and religion—an end to the supremacy of Israel or the isolation of the people of Jehovah, as exhibiting His Law and the blessings of His government to mankind. It must be remembered, however, that the isolation here commanded was only a means to an end; it was not the end itself.

It may be further observed that as soon as the danger of idolatry was at an end, the isolation of Israel largely ceased. The object of giving the people a land of their own, and supremacy among the surrounding nations, was to enable them to develop the religion which was to prepare the way for Christianity. When the religious principles of the nation were sufficiently fixed to make their political supremacy unnecessary, this supremacy was taken away.