"But of that day and hour no one knows, not even the angels of heaven, but My Father only. But as the days of Noah were, so also will the coming of the Son of Man be. For as in the days before the flood, they were eating and drinking, marrying and giving in marriage, until the day that Noah entered the ark, and did not know until the flood came and took them all away, so also will the coming of the Son of Man be. Then two men will be in the field: one will be taken and the other left. Two women will be grinding at the mill: one will be taken and the other left.

Watch therefore, for you do not know what hour your Lord is coming.

Here we see Jesus saying that there will be another day that is not knowable. Of importance Jesus begins this next section with "But of that day…" speaking of a different day entirely from the first section of Matthew 24. He introduces a new topic, distinct from the coming judgement of Israel for rejecting him (See Matthew 18) and the nations; His description of His Second Coming. He now moves in a new discussion about another day unrelated to those prior events.

What follows is this passage of His description of His coming for the Church, otherwise known as the Rapture. We must take note of the context of what follows, especially in Matthew 24:40-41 which describes people instantly disappearing from the earth (see also 1 Corinthians 15 and 1 Thessalonians 4). After this there will be a time of utter distress. Jesus' reference to the times of Noah was intended to explain what happens following the removal of the Church; a time of chaos where the world will experience the destructive effects of the Tribulation.