Jesus already in his teachings to his disciples, pointed to the fact that the Son of Man will come suddenly (Luke 17:24). So what matters is that we are prepared for this. With two examples from the Old Testament, Jesus makes this abundantly clear.
First, Jesus points to the history of Noah. Life continued as it had been, day after day. It was a life of eating and drinking. Weddings were arranged and celebrated. The people were totally absorbed in living, though Noah warned them (to obey God). The apostle Peter for a good reason called Noah in 2 Peter 2:5 the herald of righteousness.
In Genesis 6:9–11 we read, Noah was a righteous man, blameless in his generation. Noah walked with God. And Noah had three sons, Shem, Ham, and Japheth. Now the earth was corrupt in God's sight, and the earth was filled with violence.
"In the midst of that world of godless people, Noah was the herald with the (spiritual) hammer, who, by constructing an ark on dry land, continually appealed to the people to live righteously"1 (see Genesis 6:9, Genesis 6:11). But they did not listen at all to Noah’s preaching in word and deed. They did not look further than the things of every day. Life of every day absorbed them completely. In their thinking that was all that mattered. They did not take God and his commandments into account at all. But the big flood came and completely swallowed them all (see Genesis 7:20–24).
This is how it will go with people who do not prepare their hearts and minds faithfully for the coming of the Son of Man.
26 Just as it was in the days of Noah, so will it be in the days of the Son of Man.