What Does Genesis 15:16 Mean?

"In the fourth generation your descendants will come back here, for the sin of the Amorites has not yet reached its full measure." Two reasons are given for the four-hundred-year delay: the covenant descendants needed the time in Egypt to become a people large enough to inhabit the Promised Land, and the iniquity of the Amorites needed more time to develop. The land is not immediately given because the current inhabitants are still within the scope of patient divine forbearance. God will not expel the Amorites until their wickedness has fully ripened.

The theology of "the sin of the Amorites has not yet reached its full measure" is one of the most significant statements about divine patience in the Old Testament. God does not judge prematurely; He waits until judgment is warranted by the accumulation of the sin being judged. For the Amorites, that accumulation required four centuries. The same principle appears in the prophets when the nations surrounding Israel are warned that their judgments are on a timeline set by the accumulation of their own wickedness, not by arbitrary divine decision.

The Amorites, along with the other pre-Israelite inhabitants of Canaan, will be the subject of the conquest under Joshua in exactly the pattern this verse describes. The conquest is not simply a land transfer but a covenant judgment on peoples whose sin reached full measure through the centuries of Abram's descendants'' sojourn in Egypt. This theology of measured, patient, and historically timed judgment is the background of the New Testament warning that "these things were written as examples for us", God's patience with sin has a limit, and the limit is set by the internal logic of the sin itself, not by arbitrary divine decree.