Luke 21:31-34

Luke 21:31 (KJB)
So likewise ye, when ye see these things come to pass, know ye that the kingdom of God is nigh at hand.

Here Jesus sums up what He has been telling them in the way of signs of both events, the destruction of Jerusalem and His return to earth on the last day. (Mat 24:33 KJV) So likewise ye, when ye shall see all these things, know that it is near, even at the doors. Notice the word “doors” that it is plural. He is telling the disciples that when they see the signs of the approaching armies on Jerusalem then the desolation is right at the door. Then in the latter days, when the Christians see the signs in the earth and heavens, then He is at the door of His second coming.

Luke 21:32 (KJB)
Verily I say unto you, This generation shall not pass away, till all be fulfilled.

Here Jesus reverts back to the warning about the destruction of Jerusalem. The generation that He is speaking of is the one that will be present in Jerusalem in 70 A.D. (Mat 24:34 KJV) Verily I say unto you, This generation shall not pass, till all these things be fulfilled. In the parallel verse in Matthew 24:34, this is certain because He uses two demonstrative pronouns, “this” which is singular and “these” which is plural. When these words are used, it is speaking of something that is near and not distant. The demonstrative pronoun represents something that is either near or distant. If Jesus was speaking of His return, He would have used the words “that” and “those.”

Luke 21:33 (KJB)
Heaven and earth shall pass away: but my words shall not pass away.

The words of Jesus are eternal and enduring and therefore will outlast the heavens and the earth. What is also in view here is the fact that what Jesus was warning them about, the coming destruction of Jerusalem is a sure thing and it will happen. Even if the earth and heavens pass away, what He said will not pass away because all will come to pass and that will include the second coming of Christ. What also must be factored in are two other things which Christ spoke about and that is the final abode of the unbelievers which is hell and the final abode of the believers which will be the New Heavens and the New Earth. The words “pass away” in the Greek means to perish. The words of the Lord will never perish.

Luke 21:34 (KJB)
And take heed to yourselves, lest at any time your hearts be overcharged with surfeiting, and drunkenness, and cares of this life, and so that day come upon you unawares.

Overcharged - Weighed down or burdened
Surfeiting - This word appears only once in the NT.  It means “gluttony, excess, or overindulgence.”
Unawares - Suddenly or unexpected

This verse begins a paragraph showing the need for the believer to be vigilant in their Christian walk. “Take heed” is in the Imperative mood making it a command. We are commanded to pay close attention to our walk, to make sure that we are walking in the Spirit and not following the ways of the world. Back in Luke 12 we read about the servant who began to act worldly when his master had gone away. (Luke 12:45 KJV) But and if that servant say in his heart, My lord delayeth his coming; and shall begin to beat the menservants and maidens, and to eat and drink, and to be drunken; The verse we are looking at connects very strongly with the attitude of this evil servant. It may look like Jesus is never going to return and that the world is getting to be a more evil place to live. Many false Christians (and even true ones) have made friends with the world instead of seeing it as a mission field. Many have over extended themselves on finances, are drinking alcohol, sleeping around, and other worldly things. Then Jesus is telling His disciples that He will return suddenly and catch these evil servants in their sinful lifestyles. He gives special instructions to the true Christian that they are take heed that they remain vigilant in their Christian lives no matter how bad it gets or how many friends abandon us for the world. (Mat 24:44-46 KJV) Therefore be ye also ready: for in such an hour as ye think not the Son of man cometh. {45} Who then is a faithful and wise servant, whom his lord hath made ruler over his household, to give them meat in due season? {46} Blessed is that servant, whom his lord when he cometh shall find so doing. Readiness is the key to this verse.