Gen 15:13 Then the LORD said to Abram, “Know for certain that your descendants will be strangers in a foreign country. They will be enslaved and oppressed for four hundred years. 15:14 But I will execute judgment on the nation that they will serve. Afterward they will come out with many possessions. 15:15 But as for you, you will go to your ancestors in peace and be buried at a good old age. 15:16 In the fourth generation your descendants will return here, for the sin of the Amorites has not yet reached its limit.”

Why would be so long before Abrahams’ descendants would enter the promised land?

The answer given in v16 is that ‘the sin of the Amorites has not yet reached its limit.’

The designation ‘Amorites’ can stand for one or (as here) all ten (Gen 15:19–21) of the people groups of Canaan.  The extent of their sin is testified in Lev 18:24–25; 20:22–24; Deut 9:4f; 18:12; cf. 1 Kgs 14:24; 21:26; 2 Kgs 21:11; Amos 2:9.

Calvin argues that God had given the land to the Amorites, and would not dispossess them of it without good cause.  Calvin also refers to God’s patience in allowing the Amorites full opportunity for repentance, noting Paul’s teaching that ‘they who indulge themselves in sin, while the goodness and clemency of God invite them to repentance, heap up for themselves a treasure of wrath, (Rom 2:4).’  Calvin adds the pastoral comment that God’s delay in judgement gives us no excuse for lethargy.

Wiersbe stresses that God was giving the Canaanite nations opportunity to repent (cf. 2 Peter 3:8–9; Matt. 23:32).

Mathews (NAC) agrees that the delay in judging the Amorities represents God’s forbearance.  God is more ready to forgive than to condemn, and his judgement, when it finally comes, is not capricious (cf. Gen 18:20-25).

For Kidner, Joshua’s invasion (and, by implication, the other Old Testament wars) is to be seen as an act of justice, rather than of aggression.  God’s people must wait, even though waiting would cost them many years of hardship.

Leupold adopts a similar approach, noting that although we have not yet seen direct evidence of Canaanite iniquity, instances would soon appear, beginning with Sodom.

Kaiser (HSB) notes that the Amalekites deliberately targeted the struggling Israelites, picking off the weak and elderly and brutally murdering them (Deut 25:17f).  In attacking Israel, they were attempting to discredit Israel’s God. If, as some think, Haman was an Amalekite, then his proclamation that all Jews throughout the Persian Empire should be killed on a certain day (Esth 3:8-11) is evidence of the Amalkites’ unrelenting hostility towards the Jews throughout OT times.

Hartley notes that when a nation heaps up sin upon sin, God often judges such a nation by using another nation to drive out its inhabitants.  Many years later, God used the Assyrian army as the means of punishing Israel for their continued sin (Isa 10:5-19).

Waltke & Fredricks see here a pattern that is repeated elsewhere.  God judges nations only when they have become completely saturated with sin (Lev 18:24–28; 20:23). So it was with the Flood Gen 6:5, 12) and with Sodom and Gomorrah.   The same would apply even to God’s people themselves (Deut 28:36–37; 2 Kings 24:14; 25:7).

Wenham adopts a similar approach, but with little discussion or explanation.

Brueggemann reflects on the issue of ‘waiting’, but without addressing the question of the sin of the Amorites.

In his book Fight: A Christian Case for Non-Violence, Preston Sprinkle adopts an approach which is essentially the same as has been outlined above.  He then asks if the Canaanites were given a real opportunity to repent.  He answers in the affirmative, pointing to texts such as Ex 15:14–16; Josh 2:9–11; 5:1; 9:9 that show that God’s power (for example, in delivering his people from Egypt) had been broadcast far and wide among the Canaanite nations.  A specific example who knew of the God of Israel and turned to him is Rahab, Josh 2:10f.  Even thought the rest of the people of Jericho did not share her faith, they were given seven days (while the Israelites marched around their town) in which to repent.

The point is

‘that the seven-day march around the city could be viewed as another offer of grace by the God of Israel, an offer already taken up by Rahab yet rejected by the rest of Jericho’s inhabitants.’

An alternative view

In The Lost World of the Israelite Conquest, John Walton contests the whole notion of a retributive interpretation of the conquest.  He maintains that:

The Hebrew expression translated ‘not yet’ should be understood as meaning, not a transition from one state to another, but a continued state; ‘continues to be.’

The expression translated ‘(not) completed’ should be understood as meaning ‘(not) deferred’.

The word translated ‘sin’ refers more to the punishment of sin, rather than to the sin itself.  In the present case, it would refer to God’s taking the land away from the Amorites and giving it, at a future date, to the Israelites.  In other words, it refers to something that will happen to the Amorites, not to something they themselves are doing (or will do).

For Walton , the passage as a whole would read something like this:-

“Your descendants will be enslaved for 400 years in Egypt, but I will eventually punish Egypt and bring your descendants back to this land. You yourself will live a long life and will die at a ripe old age, and although I have decreed the destruction of the Amorites, that destruction won’t come upon the Amorites who are your friends and allies.”

Or, putting it slightly differently:

‘It won’t be until aſter your lifetime is over that your family will return here, because the destiny of destruction that has been decreed for the Amorites has been and will continue to be deferred.’

The above is quoted, with support, by Helen Paynter, in God of Violence Yesterday; God of Love Today?