What Does Genesis 18:20 Mean?

Then the Lord said, "The outcry against Sodom and Gomorrah is so great and their sin so grievous." The disclosure of the Sodom judgment begins with the characterization of the offense: the outcry (Hebrew: za'akah) and the grievousness of the sin. The word "outcry" is the same word used for the cry of the oppressed in the Exodus narrative, the cry of enslaved Israel heard by God in Exodus 2:23. Sodom's sin has generated exactly this kind of cry: the cry of those being wronged within the city, heard by God before any visitation. The judgment of Sodom is responsive to suffering, not arbitrary.

Sodom and Gomorrah as cities of sin are introduced in Genesis without detailed description of their sin's specific content; that content emerges in chapter 19's narrative. The "outcry" against them is what God has heard; the investigation (verse 21) will determine the precise character of what generated the cry. The pattern of hearing the outcry before acting on it is the established pattern of divine response to human wickedness in Genesis: God heard Abel's blood cry from the ground; God heard the flood generation's wickedness; God hears the Sodom cry before the investigation. The responding God is the hearing God.

The "sin so grievous" of Sodom and Gomorrah is the language of absolute moral seriousness. The prophets who later use Sodom as the paradigm case of wickedness (Isaiah 1:10, Ezekiel 16:49-50, Amos 4:11) understand the sin as comprehensively evil: pride, excess, and the failure to care for the poor, along with the violence and sexual violation that chapter 19 depicts. The complete picture of Sodom's sin is not reducible to one category but represents the systemic moral collapse of a society that has oriented itself entirely away from the covenant values of righteousness and justice. Jesus used Sodom as the reference point for societies that reject the covenant message and its messengers.