"Now learn this parable from the fig tree: When its branch has already become tender and puts forth leaves, you know that summers is near. So you also, when you see all these things, know that it is near-at the doors! Assuredly I say to you, this generation will by no means pass away till all these things take place. Heaven and earth will pass away, but My words will by no means pass away. Matthew 24:32-35 NKJV
Jesus makes a statement here that has been sometimes misunderstood, even twisted, by various people. I have run across Muslims using this to discredit the scriptures by claiming the biblical Jesus was a liar. Some anti-missionary rabbis have also turned to this with a similar motive. They wish to show that Jesus could not possibly be the Messiah. Once again, the aim is to paint Him as a liar. And then there is the eschatological position that all of the biblical end time prophecies were fulfilled in 70 AD, when Rome destroyed Jerusalem.
The statement in question is this, "Assuredly I say to you, this generation will by no means pass away till all these things take place." Therefore, it is claimed that Jesus was a liar, or false prophet because the generation of His day never lived to see His return. As for the view point, that these prophecies are now history, they claim that Jesus was merely speaking of judgement against Israel, and that happened in 70 AD. Of course Jesus did not literally return, with every every eye seeing Him, so I'm not entirely sure how they reconcile all of this, but anyway.
So lets look more carefully at what Jesus is saying here, to find out what He means. First all, remember what He has just finished saying. He has spoken of false messiahs bringing deception, wars and rumours of wars, famines, tribulation unlike anything the world has ever seen, cosmic signs, and then His visible return.
Now people have said that there have always been wars in various places, and the same for famines. What I look for here are specific wars that occur at the time of the appearance of a leader who turns out to be the antichrist. Middle eastern conflicts where an eventual coalition of ten Muslim nations where a leader emerges as its head ( Dan 7:23-24) would be what I look for. This would be that leader who makes some form of covenant with Israel for 7 Years( Dan 9:27). As the seals of Revelation are broken one by one, we will see these events take place. As this man rises to power we will see conflicts, economic disaster and famine. Perhaps this is how the mark of the beast comes into existence. Then at the midpoint of the 70th week of Daniel's prophecy this man will be revealed for who he really is and what is known as the great tribulation will be underway (Daniel 7:20-25, 9:27).
So what we need to understand is this. Jesus was describing the events leading up to His visible return. Included in this are the cosmic signs. The sun will be darkened, and the moon will turn blood red. We will see stars falling from the sky. Then He will return. Jesus was not saying that His generation would be the ones to see His return. He was telling us that the generation to be alive when these various signs began to take place, would be the generation to see His return. In Luke's gospel he says, "Now when these things begin to happen, look up and lift up your heads, for your redemption draws near" (Luke 21:28 NKJV).
As one continues to read on, Jesus uses several parables to teach us to be ready for His return. In two places He leaves the impression that it might be a long time (Matt 24:48, 25:19). In both instances a man leaves for a while, places servants in charge, and is a long time in returning. Now did Jesus mean for us to understand that He might be a while in coming again? It could very well be. At any rate He has not returned yet, so it is up to us to be faithful and ready for His return. He tells us that heaven and earth will pass away, but His words will not. Context is everything when studying scripture, and by taking this passage as a whole (Matt 24-25), and not a verse here and there, a more accurate conclusion can be reached.