"Hour" can mean a literal hour or a longer time period. For example, "Now from the sixth hour there was darkness over all the land unto the ninth hour" (Matthew 27:45). That's a literal hour. For a different example, "Because thou hast kept the word of my patience, I also will keep thee from the hour of temptation, which shall come upon all the world, to try them that dwell upon the earth" (Revelation 3:10). That hour means a time period.
Which meaning applies in these verses? "But of that day and hour knoweth no man, no, not the angels of heaven, but my Father only" (Matthew 24:36). "Therefore, be ye also ready: for in such an hour as ye think not the Son of man cometh" (Matthew 24:44). "Watch therefore, for ye know neither the day nor the hour wherein the Son of man cometh" (Matthew 25:13).
I didn't press the argument about "hour" in the first edition of my book, because I thought maybe that was being too picky. But now I think it deserves some careful examination.
When Jesus says "be ye also ready" do you suppose He wants us to be ready always? Or does He want us to wait for the day and then get ready for the specific hour of that day? Shall we be ready for a long season or for one short hour? I think we can agree that Jesus is urging continual readiness.
But why? What's the logic behind it? Suppose I'm take my wife on a long vacation, and I tell the gardener, "Now keep the lawn mowed, because you don't know when we're returning home." That makes sense. But suppose I said, "Now keep the lawn mowed at all times, because we're returning on the 15th of next month, but you don't know what hour of that day we'll arrive." That doesn't make sense.
In other words, "hour" as a time period makes sense in these Matthew verses.
Notice that He says "day and hour" and "day nor hour." Why day first, hour second? Is He saying, "You know neither the day nor the specific hour of the day"? Or is He saying, "You know neither the day nor the general season"? Which makes sense in this context?
If we don't know the day, then of course we don't know the specific hour either. Therefore, to add the word "hour" would be superfluous if He meant a literal hour. If He meant a literal hour, wouldn't He have said "hour and day"?
Therefore, the word order and the logic behind readiness both support the usage of "hour" as a general time period.
Further support comes from the parallel passage in Mark 13:3237. Although He mentions times of the day, like morning and midnight, as an illustration, again the purpose is to encourage continual readiness every day, every week, every month, every year. Verse 33 explains it in plain language: "Take ye heed, watch and pray: for ye know not when the time is." What's the word there? Time. The word means "season." For example, Acts 1:7 says, "It is not for you to know the times or the seasons." "Seasons" in Acts 1:7 is the same Greek word as "time" in Mark 13:33. Therefore, Mark confirms "hour" to mean "season."
This takes the argument far beyond the known day versus the unknown day. Not only is the day unknown, but the season also is unknown. I write this before the turn of the millennium, and I don't even know in what millennium He is returning. A post-trib rapture cannot create this degree of unexpectancy. Neither can a mid-trib rapture. Nor a three-quarters-trib rapture. Impossible.
This is not quite the same as an "any-moment" rapture that post-tribs ridicule. Perhaps there were some early moments when Christ could not have returned because of early prophecies that had to be fulfilled first. But those moments are past. Now we're facing a return of which we know neither the day nor the season.