Luke 21:26-30

Luke 21:26 (KJB)
Men's hearts failing them for fear, and for looking after those things which are coming on the earth: for the powers of heaven shall be shaken.

Then the powers of Heaven will be shaken. Not only will the physical universe be collapsing but also the kingdom of Satan will be collapsing too. He right now is in the heavens and the coming of the Lord Jesus Christ will spell the end of his kingdom and he will be shaken as he is sent to eternal damnation. (Heb 12:26 KJV) Whose voice then shook the earth: but now he hath promised, saying, Yet once more I shake not the earth only, but also heaven. The word “heavens” is plural meaning that all the heavens as we know of shall be shaken. The first which surrounds earth, the second which is the universe, and the third which is the abode of God because the judgment against sin will be that mighty.

Luke 21:27 (KJB)
And then shall they see the Son of man coming in a cloud with power and great glory.

Once the signs in the Heaven start happening, then we are to look up because the Son of man will appear in Heaven which means that Jesus is returning and now the world is seeing it and as a result, when they recognize Jesus as the one they have rejected and persecuted along with His children, they will mourn because they know their impending doom is at hand. The return of Christ is not going to be some secret rapture of the church but is going to be a mighty event for the whole world to see, including the unbelievers who are about to be taken to judgment. His power will split the heavens in two and then He will return in great glory with myriads of angels and the glories of Heaven will be poured out for all to see. In fact the second coming of Christ is going to be so awesome that the unbelieving world will want to hide from it. (Rev 6:15-17 KJV) And the kings of the earth, and the great men, and the rich men, and the chief captains, and the mighty men, and every bondman, and every free man, hid themselves in the dens and in the rocks of the mountains; {16} And said to the mountains and rocks, Fall on us, and hide us from the face of him that sitteth on the throne, and from the wrath of the Lamb: {17} For the great day of his wrath is come; and who shall be able to stand?

Luke 21:28 (KJB)
And when these things begin to come to pass, then look up, and lift up your heads; for your redemption draweth nigh.

When you see these things begin then look up for it is close. We do not have to wait for the culmination of these events, all we have to look for is the beginning of those events and then we will know the end is at hand. The unbelieving world will not know what is happening because they will be looking to the scientists for answers. If the sun becomes darkened then according to science, the world will freeze over very shortly and that would signal the end of mankind. Only those who are truly saved will know what is going on and in that time there will probably still be a rejection of truth as man tries to figure it out. We do not know how long a period it will be between the beginning and end of these events. It may be a while and that is why the world sees no way out or they are restless with great fear.

Luke 21:29 (KJB)
And he spake to them a parable; Behold the fig tree, and all the trees;

Then Jesus goes into the parable of the fig tree which speaks of the budding of the trees in concert with the coming of the Kingdom of God. Now this is called the parable of the fig tree, yet Jesus includes all the other trees which also have a time of budding and then leaves and then the shedding of those leaves in Fall.

Luke 21:30 (KJB)
When they now shoot forth, ye see and know of your own selves that summer is now nigh at hand.

Jesus uses a parable about a fig tree. When the fig tree buds and the leaves begin to appear, that is a sign the winter is over and springtime is here and summer will soon arrive. The branch is tender because the sap has congealed inside it during the winter. Something that congeals is something which goes from a liquid state to a solid state. This happens in the cheese industry during production.