Part of the ongoing Verse Quick Reference project.
Gen 18:20 And the LORD said, Because the cry of Sodom and Gomorrah is great, and because their sin is very grievous;
Gen 18:21 I will go down now, and see whether they have done altogether according to the cry of it, which is come unto me; and if not, I will know.
In Genesis 18:20, God stands with Abraham and declares that He will visit Sodom to see if the people have done exactly what He has been told that they have done. God then conditions His knowledge on the results of this test: “and if not, I will know”.
One of two things is happening here. Either God is confirming prior received reports (suggesting He does not even have current knowledge of the details of Sodom) or God is giving Sodom a test using the two angels to verify their continued behavior. The text is not written with omniscience in mind, at least not omniscience of all future events.
Bruce Ware, critical of the face value reading of the text, acknowledges the natural reading and then opts to reject it because he doesn’t like the consequences:
Again, a moment’s reflection on this text reveals the severe doctrinal implications that would follow were one to employ here the openness hermeneutic of Genesis 22:12. By God’s own admission, first, he does not presently know whether the sin of Sodom is as great as its outcry. Second, he does not know the past sin of Sodom fully, since he must see if they have done according to its outcry. Third, he is not omnipresent, since he needs to travel there and only then will be able to see what the status of their sin is; when he arrives and looks, then (and only then) he will “know.” Hermeneutical consistency, it would seem, requires that if Genesis 22:12 means that God learned something new, as open theists claim, then Genesis 18:21 means that God does not know all of the past or present and that he is spatially confined. So which should it be? Shall we follow the openness approach consistently and deny even more of God’s attributes than have already been trimmed away?
Bruce A. Ware. God’s Lesser Glory: The Diminished God of Open Theism (Kindle Locations 700-706). Kindle Edition.