The destruction of the Canaanites is one of the most perplexing of the ethical problems in the Old Testament.  How could God condone, let alone command, the treatment meted out by his people on the previous inhabitants of the land?

J. Oswald Sanders makes some helpful points:-

1.  The nations were given the opportunity to make peace with Israel, Deut 20:10.  This is what happened in the case of the Gibeonites.

2.  These nations had been granted long probation and had received many unproductive warnings from Abraham, Melchisedec and others.  They knew of the judgement on Sodom.  Israel had been on their doorstep for 40 years – a further period of respite during which they could have repented.

3.  The reason for the extermination was not military or territorial, but moral and spiritual.  These nations were idolatrous demon-worshippers.  They indulged in utterly depraved practices.  God could excuse their abominations no longer.  See Deut 18:10-12.

4.  One of their number, Rahab, heeded God’s warnings, repented, and cast herself on the mercy of God.  She and her family were spared.  The same mercy was open to them all.

5.  The destruction of the Canaanites was prophylactic in purpose – to prevent the spread of moral and spiritual infection.  In the event, the wicked nations were not utterly destroyed, and Israel soon imitated their idolatry and immorality, and were themselves expelled from Canaan for their sins.

6.  Israel was claiming territory which belonged to God, and which had been given by him to them as an inheritance.  See Acts 17:26.

7.  The problem of the severity of the divine judgements is not limited to the Old Testament.  The teaching of the New Testament is not less, but more severe.  And the most solemn warnings came from the lips of our Lord himself.

‘For the Christian there can no truce in his battle with sin and the powers of evil.  We must learn the lesson Israel failed to master – no quarter must be granted to our spiritual foes.’

See J.O. Sanders, The Christian’s Promised Land, 27-29.