Mark 13:21 - 14:2
I've established the fact that I believe this passage to mostly mean the destruction of Jerusalem's temple in 70. But it also has meaning for us today as, Jesus will come back in power and glory.
I listened to RC Sproul preach on this passage in Luke a few weeks ago. He brought up the conundrum that Jesus said that he would appear in the clouds in power and glory and that generation would not pass away until it happened. And it's mostly true. John the Apostle lived until about 100 and was the last living apostle, the only one who died of natural causes. But many people are confused because when the temple was destroyed, people did not see Jesus coming in the clouds.
RC Sproul answered this by saying that Jesus's Spirit was there in full force in judgment of the Jews who did not accept him as their Messiah, which is true. And it's true that when he comes to complete history and to consummate his Kingdom, then we will all see him. But verse 26 of chapter 13 says "they will see the Son of Man coming in the clouds with great power and glory." People did not literally see Jesus in the clouds.
But then again, when Stephen died in Acts 7, Scripture records that he could see Jesus in the clouds as his enemies stoned him. Could this refer to the people that died that day when Rome destroyed the temple? Perhaps. Maybe he was there but they were too confused to notice. Or, like RC said, it was invisible, but people could see the events coming before they happened.
I do know this. God's word is true. Jesus will come in a most complete way some day and we're going to know it. All mysteries will be cleared up then.
Jesus also proclaims the mystery that even he as the Son of God incarnate did not know when the end will come. First, it puts to shame anyone who predicts the date of Christ's return. If he did not know, then you certainly don't know more than him and you don't know. Second, it emphasizes that as a man, Jesus was completely God and completely human and did not draw from his deity to cheat through his life. He obeyed God in every way. It also shows that he is different from God the Father even though they are one God. This mystery is much clearer then the previous one that I mentioned.
And finally, Jesus was very much threatening the Jewish leaders, their temple and their way of life. They knew he was right and that they would suffer for eternity one day, but they never repented and only conspired how they could take Jesus's life. Don't be like that. Repent of your sins, come to Jesus, and he will save you. Do not be so satisfied with your ways that when Jesus comes to change them that you decide to kill him and rid your lives of him. Either you will suffer his wrath for eternity or you will enjoy his love for eternity because Jesus took the punishment for your sins. Go to Jesus in repentance and he will not turn you away.