In the Olivet Prophecy and concerning his parousia (Matthew 24:3), Jesus told his disciples that no man knew that day and hour, not even the angels, but his Father only (Matthew 24:36). What does it mean, first of all, ‘that day and hour’? Was Jesus speaking of the night and day portions of a single day and a single 60-minute hour of a single day? I don’t think this was what he had in mind, nor do I believe the Apostles normally divided their day that closely. We do today, but I don’t think they did back then. They had three and four hour watches during the night, and the hour was important to the employer, and even for daily worship the hour was important, but normally speaking, they didn’t divide their day up into 24 one hour periods.
For example, a day (G2250) could mean a single day from sunset to sunset, or it could refer to the daytime portion of a single day, from sunrise to sunset (John 11:9). It could also be used metaphorically of the years of one’s life (Luke 1:7, 18; 2:36). So, Jesus knew that the things he spoke of in Matthew 24 would be in a single generation of time (Matthew 24:34), but he couldn’t tell, perhaps, which decade of years within that generation that his parousia (G3952) would occur—that would be not knowing the day. The hour is a shorter span of time. If, therefore, the day is known, it does not mean that the hour would be known as well.
The hour is hora in the Greek (G5610). It could mean the twelfth part of the daylight portion of the day (John 11:9), or it could mean a single moment in time (Luke 2:38). It could also point to the night portion of the day in which evil is done (Luke 22:53), or it could refer to a season of a man’s life, lasting a few years (John 5:33-35) or perhaps for a few weeks (2Corinthians 7:8) or perhaps months (Philemon 1:15). Therefore, the hour refers to a shorter and a more exact period of time within that generation of which Jesus spoke (Matthew 24:34).
While it is true that Jesus said he didn’t know the day and hour of his coming (Mark 13:32), it doesn’t follow that he wouldn’t later know the hour when he was with his Father in heaven. For example, Jesus told the disciples that some things he would have liked to have told them they wouldn’t be able to receive during the time of his earthly ministry (John 16:12), but later the Holy Spirit would recall to them things Jesus said and did, and they would understand (John 16:13-14). So, Jesus didn’t tell his disciples everything he intended them to know before he left to be with his Father in heaven, but he later told them those things through the Holy Spirit which was given to them on Pentecost.
Moreover, John tells us that the Father, who knew the day and hour, gave a ‘revelation’ or a disclosure to Jesus, so that he might give that ‘revelation’ or disclosure to his disciples, which involved “things that must shortly come to pass” (Revelation 1:1), and those things which must shortly come to pass involved the Lord “coming quickly” (Revelation 3:11; 22:7, 12, 20). Therefore, it seems that the Father revealed the hour to Jesus, and he, in due course, revealed it to his disciples through John in what we know as the book of Revelation or the Apocalypse!
We don’t know why, the day and hour couldn’t be revealed, even to Jesus, during his public ministry. We can only speculate. For example, it may be that the hour could have occurred sooner than 70 AD. During the first persecution that began with Stephen (Acts 8:1-3), we aren’t told how severe that may have been (cf. Acts 9:1-2). Josephus tells us that Gaius Caesar planned to set up an idol of himself in the Temple at Jerusalem, and Petronius, the president of Syria came with his armies and wintered at Ptolemais, just north of Caesarea along the Mediterranean coast, planning to erect the idol in the Most Holy Place in the Temple at winter’s end. The Jews came to him in peaceful demonstration, pleading with him to turn back. He finally consented to request Caesar to reconsider, and in the meantime Gaius was assassinated.
What happened? Of course nothing can be placed in cement, but Luke does tell us in Acts that the churches of Judea, Samaria and Galilee had rest. In other words, the persecution that had begun with Stephen’s death ceased (Acts 9:31). Theophilus, the high priest, repented of the matter perhaps through Luke’s presenting him of his Gospel, which mentioned “Jerusalem surrounded by armies” in the Olivet Discourse (Luke 21:20), instead of the “abomination of desolation” in Matthew and Mark. If this is so, that Luke influenced Theophilus, the high priest, then one reason the hour couldn’t be revealed during Jesus’ public ministry was, because Jerusalem needed to be given time to repent (cf. Revelation 2:20-21).
So, simply because the day and hour couldn’t be revealed at one time, doesn’t mean it could be revealed at another time. In fact, the Lord tells us through the prophet Amos, that he will do absolutely nothing, unless he first tells what he is about to do to his servants (Amos 3:7). Therefore, it seems logical the revelation of the day and hour had to be disclosed to Jesus’ disciples sometime before Jesus coming to judge Jerusalem and destroy the Temple (cf. Matthew 26:64).