In this passage Jesus told His disciples that His return would come—“that He is near, right at the door” (v. 33)—when certain end time events would occur: the antichrist would disrupt the temple (the abomination of desolation), the great tribulation, the darkening of the sun and moon, the stars would fall, the powers of the heavens will be shaken, people on the earth will mourn, persecutions, false prophets, earthquakes, and famines (vv. 15-31). And He told them that these events would take place within the lifetime of that generation (v. 34).
Verses 36 through 39 describes the unpreparedness of the unbelieving people at the time of “this generation.” To be sure, the second phase of His coming is what is spoken of in this text—that unbelievers will be unprepared for the coming judgment just as they were in the days of Noah and in the days of Lot.
But I think we can also apply the lesson here to unbelievers now, for all unbelievers who miss the rapture will miss it because they don’t know when He is coming (v. 36), they will be unprepared to meet Him, and they have no spiritual understanding (v. 39).
“Now learn the parable from the fig tree: when its branch has already become tender, and puts forth its leaves, you know that summer is near; 33 even so you too, when you see all these things, recognize that He is near, right at the door. 34 “Truly I say to you, this generation will not pass away until all these things take place. 35 “Heaven and earth will pass away, but My words shall not pass away. 36 “But of that day and hour no one knows, not even the angels of heaven, nor the Son, but the Father alone. 37 “For the coming of the Son of Man will be just like the days of Noah. 38 “For as in those days which were before the flood they were eating and drinking, they were marrying and giving in marriage, until the day that Noah entered the ark, 39 and they did not understand until the flood came and took them all away; so shall the coming of the Son of Man be.