“Be ... ready, because at what hour you know not the Son of man will come.”
Catholics refer to the last book of the Bible as "the Apocalypse." That comes from the Greek words that mean “uncovering” (ἀποκάλυψις) However, we use the word “apocalyptic” to describe something that doesn't seem to be a simple “uncovering.” Usually, “apocalyptic” refers to something destructive, and even the final destruction of our world. There are also the implications that events may be out of logical sequence, and that symbols may represent some things other than their normal subjects. These implications are some of the reasons why many people have difficulty reading the last book of the Bible.
Today's Gospel is an example of an apocalyptic writing. It is hard to know when the events it describes are going to take place. Our Lord refers to seeing “the abomination of desolation, which was spoken of by Daniel the prophet....” Daniel wrote in the second century BC, and may have been prophesying the desecration of the Jerusalem Temple, with an Idol of Zeus in 168 B.C. Or, Jesus may have been applying the prophesy to to the destruction of the Temple by the Romans in 70 A.D. (The Emperor Hadrian replaced it with a temple to Jupiter around 120 A.D.) Perhaps He referred to the persecutions of Christians by various forces over the centuries—each bringing desolation to those wanting to practice the Faith. Maybe Jesus referred to an event far in His future, like the replacement of Holy Mass with the worship of idols. Yet, maybe, Jesus was referring to an action by the Antichrist near the end of the world.
So, what does today's Gospel predict. Well it did in fact predict the destruction of Jerusalem—although the description in Luke xix was somewhat more useful for the Christians who decided to flee the city. The Romans did, in fact, erect a shrine honoring Jupiter (the Roman equivalent of the Greek “god” Zeus. But the destruction of the Jewish Temple was less significant than it would have been before the crucifixion of Christ—for with His death the sacrifices of the Temple were no longer acceptable to God, having been replaced by the Holy Sacrifice of the Mass.
In our day we have seen the introduction of idol worship, but there are still many places where Holy Mass is offered. It is easy to see the modernists as the “false Christs and false prophets,” but not everyone has gone over to modernism. Today, mankind is capable of destroying itself, but it has been capable of doing so for seventy years or so, and has refrained from destroying itself thus far. It is possible that the Gospel's prophecy will be fulfilled in a future age. We have not seen the physical signs mentioned, not have seen “the Son of man coming in the clouds of heaven.”
We might ask why Jesus would have left us such a warning that would be so difficult to identify by current events. If we read but one more verse of the Gospel, we see that our uncertainty was intentional: “But of that day and hour no one know, not the angels of heaven, but the Father alone.” In fact this uncertainty about our end is reinforced by a number of our Lord's sayings. The end of the world and the General Judgment will come someday, but even if it is far in the future, our own personal end will surely come at a day and time quite unknown to us. Some of us may have the benefit of an illness, and the ability to have a priest at our death bed. But there is no guarantee! One could get hit by a bus!
The only sure way to avoid an un‑provided death is to remain habitually in the state of grace.
Not knowing when the end will come may seem a bit frightening, But we do have the means of always being ready. We have the Mass and the Sacraments! We have prayer, and the support of the Blessed Virgin and the Saints. Above all, we know what God expects of us—we can examine our consciences and be forgiven of our sins in Sacramental Confession.
So: “Be ... ready, because at what hour you know not the Son of man will come.”
 Matthew xxiv: 44 http://www.drbo.org/cgi-bin/d?b=drl&bk=47&ch=24&l=44-#x
 Gospel: Matthew xxiv: 15—35 http://www.drbo.org/cgi-bin/d?b=drl&bk=47&ch=24&l=15-#x
 Luke xix: 41-47 http://www.drbo.org/cgi-bin/d?b=drl&bk=49&ch=19&l=41-#x
 Verse 36 http://www.drbo.org/cgi-bin/d?b=drl&bk=47&ch=24&l=36-#x