Who is "This Generation" referring to ?

A plain reading of the text points to the generation Jesus was speaking to. The other position held is that Jesus was referring to a future generation other than the generation Jesus was speaking to. Although Scripture applies to all Christians of all generations in a general sense, this was a direct prophecy to the people He was speaking to. 

Mark 13:1-37

As He was going out of the temple, one of His disciples *said to Him, “Teacher, behold what wonderful stones and what wonderful buildings!” And Jesus said to him, “Do you see these great buildings? Not one stone will be left upon another which will not be torn down.” As He was sitting on the Mount of Olives opposite the temple, Peter and James and John and Andrew were questioning Him privately,  “Tell us, when will these things be, and what will be the sign when all these things are going to be fulfilled?” And Jesus began to say to them, “See to it that no one misleads you.  Many will come in My name, saying, ‘I am He!’ and will mislead many. When you hear of wars and rumors of wars, do not be frightened; those things must take place; but that is not yet the end. For nation will rise up against nation, and kingdom against kingdom; there will be earthquakes in various places; there will also be famines. These things are merely the beginning of birth pangs. “But be on your guard; for they will deliver you to the courts, and you will be flogged in the synagogues, and you will stand before governors and kings for My sake, as a testimony to them. The gospel must first be preached to all the nations. When they arrest you and hand you over, do not worry beforehand about what you are to say, but say whatever is given you in that hour; for it is not you who speak, but it is the Holy Spirit.  Brother will betray brother to death, and a father his child; and children will rise up against parents and have them put to death.  You will be hated by all because of My name, but the one who endures to the end, he will be saved. “But when you see the abomination of desolation standing where it should not be (let the reader understand), then those who are in Judea must flee to the mountains. The one who is on the housetop must not go down, or go in to get anything out of his house;  and the one who is in the field must not turn back to get his coat. But woe to those who are pregnant and to those who are nursing babies in those days!  But pray that it may not happen in the winter. For those days will be a time of tribulation such as has not occurred since the beginning of the creation which God created until now, and never will. Unless the Lord had shortened those days, no life would have been saved; but for the sake of the elect, whom He chose, He shortened the days.  And then if anyone says to you, ‘Behold, here is the Christ’; or, ‘Behold, He is there’; do not believe him; for false Christs and false prophets will arise, and will show signs and wonders, in order to lead astray, if possible, the elect. But take heed; behold, I have told you everything in advance. 'But in those days, after that tribulation, the sun will be darkened and the moon will not give its light,  and the stars will be falling from heaven, and the powers that are in the heavens will be shaken.  Then they will see the Son of Man coming in clouds with great power and glory.  And then He will send forth the angels, and will gather together His elect from the four winds, from the farthest end of the earth to the farthest end of heaven.“Now learn the parable from the fig tree: when its branch has already become tender and puts forth its leaves, you know that summer is near.  Even so, you too, when you see these things happening, recognize that He is near, right at the door.  Truly I say to you, this generation will not pass away until all these things take place. Heaven and earth will pass away, but My words will not pass away.  But of that day or hour no one knows, not even the angels in heaven, nor the Son, but the Father alone.“Take heed, keep on the alert; for you do not know when the appointed time will come.  It is like a man away on a journey, who upon leaving his house and putting his slaves in charge, assigning to each one his task, also commanded the doorkeeper to stay on the alert. Therefore, be on the alert—for you do not know when the master of the house is coming, whether in the evening, at midnight, or when the rooster crows, or in the morning— in case he should come suddenly and find you asleep.  What I say to you I say to all, ‘Be on the alert!’”

Matthew 24:1-31

Jesus came out from the temple and was going away when His disciples came up to point out the temple buildings to Him. And He said to them, “Do you not see all these things? Truly I say to you, not one stone here will be left upon another, which will not be torn down.” As He was sitting on the Mount of Olives, the disciples came to Him privately, saying, “Tell us, when will these things happen, and what will be the sign of Your coming, and of the end of the age?” And Jesus answered and said to them, “See to it that no one misleads you. For many will come in My name, saying, ‘I am the Christ,’ and will mislead many. You will be hearing of wars and rumors of wars. See that you are not frightened, for those things must take place, but that is not yet the end. For nation will rise against nation, and kingdom against kingdom, and in various places there will be famines and earthquakes. But all these things are merely the beginning of birth pangs. “Then they will deliver you to tribulation, and will kill you, and you will be hated by all nations because of My name. At that time many will fall away and will betray one another and hate one another. Many false prophets will arise and will mislead many. Because lawlessness is increased, most people’s love will grow cold. But the one who endures to the end, he will be saved.  This gospel of the kingdom shall be preached in the whole world as a testimony to all the nations, and then the end will come. “Therefore when you see the abomination of desolation which was spoken of through Daniel the prophet, standing in the holy place (let the reader understand),  then those who are in Judea must flee to the mountains. Whoever is on the housetop must not go down to get the things out that are in his house. Whoever is in the field must not turn back to get his cloak.  But woe to those who are pregnant and to those who are nursing babies in those days!  But pray that your flight will not be in the winter, or on a Sabbath. For then there will be a great tribulation, such as has not occurred since the beginning of the world until now, nor ever will.  Unless those days had been cut short, no life would have been saved; but for the sake of the elect those days will be cut short.  Then if anyone says to you, ‘Behold, here is the Christ,’ or 'There He is,’ do not believe him. For false Christs and false prophets will arise and will show great signs and wonders, so as to mislead, if possible, even the elect.  Behold, I have told you in advance.  So if they say to you, ‘Behold, He is in the wilderness,’ do not go out, or, ‘Behold, He is in the inner rooms,’ do not believe them. For just as the lightning comes from the east and flashes even to the west, so will the coming of the Son of Man be.  Wherever the corpse is, there the vultures will gather.  “But immediately after the tribulation of those days the sun will be darkened, and the moon will not give its light, and the stars will fall from the sky, and the powers of the heavens will be shaken. And then the sign of the Son of Man will appear in the sky, and then all the tribes of the earth will mourn, and they will see the Son of Man coming on the clouds of the sky with power and great glory.  And He will send forth His angels with a great trumpet and they will gather together His elect from the four winds, from one end of the sky to the other.

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