I suppose this is a theological question, these particular verses always intrigued me, mainly because it covers two interesting issues: Mormons and prophecy.
"At that time if anyone says to you, 'Look, here is the Christ!' or, 'There he is!' do not believe it. 24For false Christs and false prophets will appear and perform great signs and miracles to deceive even the elect—if that were possible. 25See, I have told you ahead of time.
26"So if anyone tells you, 'There he is, out in the desert,' do not go out; or, 'Here he is, in the inner rooms,' do not believe it. 27For as lightning that comes from the east is visible even in the west, so will be the coming of the Son of Man. 28Wherever there is a carcass, there the vultures will gather.
29"Immediately after the distress of those days
" 'the sun will be darkened,
and the moon will not give its light;
the stars will fall from the sky,
and the heavenly bodies will be shaken.'[c]
30"At that time the sign of the Son of Man will appear in the sky, and all the nations of the earth will mourn. They will see the Son of Man coming on the clouds of the sky, with power and great glory. 31And he will send his angels with a loud trumpet call, and they will gather his elect from the four winds, from one end of the heavens to the other.
32"Now learn this lesson from the fig tree: As soon as its twigs get tender and its leaves come out, you know that summer is near. 33Even so, when you see all these things, you know that it[d]is near, right at the door. 34I tell you the truth, this generation[e] will certainly not pass away until all these things have happened. 35Heaven and earth will pass away, but my words will never pass away."
http://www.biblegateway.com/passage/?book_id=47&chapter=24&version=31
Does that mean the Mormons are wrong -- Jesus in America?
"36"No one knows about that day or hour, not even the angels in heaven, nor the Son,[f] but only the Father. 37As it was in the days of Noah, so it will be at the coming of the Son of Man. 38For in the days before the flood, people were eating and drinking, marrying and giving in marriage, up to the day Noah entered the ark; 39and they knew nothing about what would happen until the flood came and took them all away. That is how it will be at the coming of the Son of Man. 40Two men will be in the field; one will be taken and the other left. 41Two women will be grinding with a hand mill; one will be taken and the other left.
42"Therefore keep watch, because you do not know on what day your Lord will come. 43But understand this: If the owner of the house had known at what time of night the thief was coming, he would have kept watch and would not have let his house be broken into. 44So you also must be ready, because the Son of Man will come at an hour when you do not expect him. "
http://www.biblegateway.com/passage/?book_id=47&chapter=24&version=31
Does that mean the book of Revelations and any sort of prophetic predictions of the end of days are pointless?