The presence of Christ is not compared to the flood, but to the days of Noah, the days that were before the flood. As the days of Noah were not days before Noah’s time, neither are the days of the Son of man days before the Son of man’s presence. Noah was present before the flood. Christ is present before the passing away of the heavens [religious systems] and earth [social order] of this present evil world. [II Pet. 3:10-13]

Matt. 24:37-39 "But as the days of Noe were, so shall also the presence [parousia] of the Son of man be. For as in the days that were before the flood they were eating and drinking, marrying and giving in marriage, until the day that Noe entered into the ark, and knew not until the flood came, and took them all away; so shall also the presence [parousia] of the Son of man be."

The contrast is not the wicked being destroyed, but that people were ignorant of the coming flood and "knew not until the flood came." The world will go on with its eating, drinking, planting, building, and marrying, not mentioned as sinful doings, but as indicative of their ignorance of our Lord’s presence and of the trouble that will prevail in the world. The world pursues the ordinary, proper affairs of life, ignorant of the impending catastrophe.

II Pet. 3:3,4 "...there shall come in the last days scoffers...saying, Where is the promise of his presence [parousia]? For...all things continue as they were from the beginning of the creation."

As Noah preached 120 years before the flood and did not convert his audience, so the world will not be converted to Christianity before the destruction of this present evil world.