Why did the Lord permit Israel to war against people in the land of promise?

Keith H. Meservy: In answering this question one must briefly look at the conditions under which any people have a right to possess land.

It is significant that when the Lord promised Canaan to Abraham, he did not give him an immediate right to it, but only a promise of future possession. In Abraham’s day the inhabitants of the land had a claim to it, but they would forfeit this right in the future as they increased in iniquity. Israel could then become the rightful claimant. (Gen. 15:16; 1 Ne. 17:32–40; cf. Ether 2:8–9.)

True, we do not have extensive accounts about the people of Canaan, but we do know that by the time of Moses and Joshua, the Canaanites (or Amorites) had become grossly wicked, for the Lord warned Israel repeatedly not to allow any of the Canaanite ways of life to infiltrate her own. Some of these iniquities were sins of the flesh: adultery, incest, bestiality, and homosexuality. He commanded the Israelites: “Defile not ye yourselves in any of these things: for in all these the nations are defiled which I cast out before you: And the land is defiled: therefore I do visit the iniquity thereof upon it. … For whosoever shall commit any of these abominations, even the souls that commit them shall be cut off from among their people.” (Lev. 18:24–29. Italics added. Cf. Lev. 20.)

Such individuals, having proven during their mortal probation that they were evilly disposed, filled the purpose of their creation and became subject to the Lord’s judgments in this world. (D&C 76:103–104.) Rather than allowing them to continue to pollute the earth by their wickedness and to contaminate the unborn generations by their perversions, the Lord’s righteous judgments took them from the earth. He did this by various means—floods, fires, famines, earthquakes, and so forth. He also used the sword. The Jaredites, Nephites, Israelites, Jews, and Laban all felt its terrible swift action in their lives.

The Israelites were given the unpleasant task of carrying out the Lord’s judgment against the Canaanites. They were ordered not to allow compassion to overrule their specific charge to destroy (Deut. 7:1–3); neither were they, after they dispossessed the former inhabitants, to conclude they had been successful because they were such a righteous people, for they had not attained that state. They were commanded to remember why the former inhabitants were no longer there. (Deut. 9:4–6.)

The Lord cannot look upon sin with the least degree of allowance (D&C 1:31); he is constantly at war with it. The Israelites waged war against the Canaanites because the Lord commanded them to. (This is the same reason why Nephi killed Laban.) It was part of the Lord’s overall struggle against unrighteousness. To carry out the Lord’s commandment required an act of obedience on their part, and it showed whose side they were on in the great struggle against evil.

We do not know why the Lord required them to do this; maybe they had to help acquire their homeland, so it would not come totally as a free gift from the Lord. Maybe the Lord was showing them some of the consequences of great wickedness. Whatever the ultimate explanation, we know that the Lord’s ways are righteous, even though we presently understand them only in part.