In 2:22 and 3:1 the nations are left so that God can ‘test’ or ‘know’ Israel. And in 3:1-2 the nations are left so that Israel can ‘learn’ or ‘know’ … ? We might expect ‘God’, but the answer is ‘war’! This is not because war is itself a good thing. The answer is that through warfare and threat Israel will learn (know, experience) obedience (3:4).
The main threat to Israel is not enemy defeat, but covenant disloyalty. The threat posed by the nations is not first and foremost a military threat, but a moral threat – the threat of compromise, seduction and temptation.
So when Israel fails to drive out the foreign nations, it is not a military failure, but a failure of faith. They have chosen compromise and with it the threat of covenant disloyalty. They may begin to worship others gods. ‘It is as though the entire course of Israel’s life in the land is to be an enactment of the first commandment or a refusal of that commandment.’ (Walter Brueggemann)
So war, in this context, is a gift. It highlights the fact that foreign nations are a threat. If foreign nations poses a military threat then they are less likely to become a source of spiritual temptation. Moreover the threat of war means every generation must decide for itself to trust in Yahweh in the face of the enemy. War becomes the trial that tests and proves the faith of God’s people (1 Peter 1:6-7).
Why should that kind of knowledge [of war] be so crucial? The answer must surely be that it is just that, the conflict with other nations, which enables Israel to know her God. Her oppressors in Egypt, her opponents during the wilderness journey, the occupants of the land she was to take over, each in turn compelled the Lord’s own nation to recognise something more of what made him, and therefore her, distinctive. Over against every ly alternative, inadequate or perverse, hectoring or seductive, the God of Israel became increasingly clearly defined as the Way, the Truth, and the Life. (Michael Wilcock)