17:20-37 The kingdom of God was among the Jews, or rather within some of them. It was a spiritual kingdom, set up in the heart by the power of Divine grace. Observe how it had been with sinners formerly, and in what state the judgments of God, which they had been warned of, found them. Here is shown what a dreadful surprise this destruction will be to the secure and sensual. Thus shall it be in the day when the Son of man is revealed. When Christ came to destroy the Jewish nation by the Roman armies, that nation was found in such a state of false security as is here spoken of. In like manner, when Jesus Christ shall come to judge the world, sinners will be found altogether regardless; for in like manner the sinners of every age go on securely in their evil ways, and remember not their latter end. But wherever the wicked are, who are marked for eternal ruin, they shall be found by the judgments of God.

24. as lightning … so … the Son of man—that is it will be as manifest. The Lord speaks here of His coming and manifestation in a prophetically indefinite manner, and in these preparatory words blends into one the distinctive epochs [Stier]. When the whole polity of the Jews, civil and ecclesiastical alike, was broken up at once, and its continuance rendered impossible by the destruction of Jerusalem, it became as manifest to all as the lightning of heaven that the kingdom of God had ceased to exist in its old, and had entered on a new and perfectly different form. So it may be again, ere its final and greatest change at the personal coming of Christ, and of which the words in their highest sense are alone true.