John Calvin on Genesis 18:20

20. The cry of Sodom . The Lord here begins more clearly to explain to Abraham his counsel concerning the destruction of the five cities; although he only names Sodom and Gomorrah, which were much more famous than the rest. But before he makes mention of punishment, he brings forward their iniquities, to teach Abraham that they justly deserved to be destroyed: otherwise the history would not tend to instruction. But when we perceive that the anger of God is provoked by the sin of man, we are inspired with a dread of sinning. In saying that the “cry was great,” “Clamorem pro scelerum gravitate multiplicatum fuisse.” he indicates the grievousness of their crimes, because, although the wicked may promise themselves impunity, by concealing their evils, and although these evils may be silently and quietly borne by men; yet their sin will necessarily sound aloud in the ears of God. Therefore this phrase signifies, that all our deeds, even those of which we think the memory to be buried, are presented before the bar of God, and that they, even of themselves, demand vengeance, although there should be none to accuse.