Luke 10:12

I say unto you, it shall be more tolerable in that day for Sodom, than for that city.

In that day ... is a reference to the final judgment which shall terminate the dispensation of grace. The Saviour's use of "that day" in this passage, where its primary reference would appear to apply to the "coming nigh" of the kingdom, shows that the kingdom of God will "come" in a more exalted state at the final judgment. Peter's reference to Christians entering into "the external kingdom" (2 Peter 1:11) also sheds light on this.

Sodom ... was a grossly wicked city whose very name came to be associated with depravity; but their carnal sins in the sight of God were actually less reprehensible than the arrogant rejection of the Redeemer by the cities of Israel. Sodom was destroyed by fire from heaven (Genesis 19:1-26). The greater sin of the cities of Israel derived from their refusing to see the Light of all nations, an opportunity Sodom did not have.