As if he said, If at the coming of Antichrist, his fame shall be spread abroad, as though Christ had appeared, go not out, nor follow him. For it cannot be that He who was once seen on earth, shall any more dwell in the corners of the earth. It will therefore be he of whom we speak, not the true Christ. For this is the clear sign of the second coming of our Saviour, that suddenly the lustre of His coming shall fill the whole world; and so it follows, For as the lightning that lighteneth, &c. For He will not appear walking upon the earth, as any common man, but will illuminate our whole universe, manifesting to all men the radiance of His divinity.
He who knows the signs of the coming judgment also knows the end. Why would he not know? He is like flashing lightning, since as the Light, the Son of God illumines the inner part of the heavenly mystery. “In that hour,” it says. He also knows the hour, but he knows it for himself, he does not know it for me. He then suitably asserts that the cause of the flood, fire and of the judgment proceeded from our sins, because God did not create evil, but our actions devised it for themselves.
When our Lord said, The kingdom of God is within you, He would fain prepare His disciples for suffering, that being made strong they might be able to enter the kingdom of God; He therefore foretells to them, that before His coming from heaven at the end of the world, persecution will break out upon them. Hence it follows, And he said unto the disciples, The days will come, &c. meaning that so terrible will be the persecution, that they would desire to see one of His days, that is, of that time when they yet walked with Christ. Truly the Jews ofttimes beset Christ with reproaches and insults, and sought to stone Him, and ofttimes would have hurled Him down from the mountain; but even these seem to be looked upon as slight in comparison of greater evils that are to come.
Now His disciples supposed that He would go to Jerusalem, and would at once make a manifestation of the kingdom of God. To rid them therefore of this belief, He informs them that it became Him first to suffer the Life-giving Passion, then to ascend to the Father and shine forth from above, that He might judge the world in righteousness. Hence He adds, But first must he suffer many things, and be rejected of this generation.
He now speaks to the holy disciples as his true companions. He says, “The days will come when you will desire to see one of the days of the Son of man, and will not see it.” … He would have them prepared for all that can cause people grief. He wants them ready to endure patiently so that approved they may enter the kingdom of God. He warns them that before his coming from heaven at the consummation of the world, tribulation and persecution will precede him. They will wish to see one of the days of the Son of man, such as those when they were still going around with Christ and speaking with him.
At the end time of the world, he will not descend from heaven obscurely or secretly, but with godlike glory and as dwelling in the light which no one can approach. He declared that his coming will be like the lightning. He was born indeed in the flesh of a woman, to fulfill the dispensation for our sakes. For this reason, he emptied himself, made himself poor, and no longer showed himself in the glory of the Godhead. The season and the necessity of the dispensation summoned him to this humiliation. After his resurrection from the dead, ascension into heaven, and enthronement with God the Father, he will descend again. He will not descend with his glory withdrawn or in the lowliness of human nature. In the majesty of the Father with the companies of the angels guarding him, he will stand before him as God and Lord of all. He will come as the lightning, and not secretly.
That they might know that he was about first to undergo his saving passion, abolish death by the death of his flesh, put away the sin of the world, destroy the ruler of this world, ascend to the Father and in due time appear to judge the world in righteousness, he says that he must first suffer many things.
Or, by the day of Christ He signifies His kingdom, which we hope will come, and He rightly says, one day, because there shall no darkness disturb the glory of that blessed time. It is right then to long for the day of Christ, yet from the earnestness of our longing, let us not vision to ourselves as though the day were at hand. Hence it follows, And they shall say to you, Lo here! and, Lo there!
And he well says, that lighteneth out of the one part under heaven, because the judgment will be given under the heaven, that is, in the midst of the air, as the Apostle says, We shall be caught up together with them in the clouds. (1 Thess. 4:17.) But if the Lord shall appear at the Judgment like lightning, then shall no one remain hidden in the deep of his heart, for the very brightness of the Judge pierces through him; we may also take this answer of our Lord to refer to His coming, whereby He comes daily into His Church. For ofttimes have heretics so vexed the Church, by saying that the faith of Christ stands in their own dogma, that the faithful in those times longed that the Lord would if it were possible even for one day return to the earth, and Himself make known what was the true faith. And you shall not see it, because it need not that the Lord should again testify by a bodily presence that which has been spiritually declared by the light of the Gospel, once scattered and diffused throughout the whole world.
He means the generation not only of the Jews, but also of all wicked men, by whom even now in His own body, that is, His Church, the Son of man suffers many things, and is rejected. But while He spake many things of His coming in glory, He inserts something also concerning His Passion, that when men saw Him dying, whom they had heard would be glorified, they might both soothe their sorrow for His sufferings by the hope of the promised glory, and at the same time prepare themselves, if they love the glories of His kingdom, to look without alarm upon the horrors of death.
For their life was then without trouble, for Christ took care of them and protected them. But the time was coming when Christ should be taken away, and they should be exposed to perils, being brought before kings and princes, and then they should long for the first time and its tranquillity.
And they will say to you: Look, there. Do not go, do not hurry. Although this sentence can be understood not only for a time, but also for a person. And indeed for a time, because there arose some who, calculating the courses of ages, would say they had found the certain year, day, and hour of the end of the world, against the authority of the Lord saying: It is not for you to know the times or the moments (Acts I). As for the person, because many heretics came against the Church, and many will come, who assert themselves to be Christs, the first of whom is Simon Magus, and the last, greater than others, is the Antichrist. Therefore, if anyone says to you, Look here, look there, that is, that in this or that person, or hour, the kingdom of God is coming or is going to come, they are not to be followed, who do not fear to seek higher things and to say unspeakable things.
[AD 339] Eusebius of Caesarea on Luke 17:22-25