Mark 13:27
And then shall he send his angels, and shall gather together his elect from the four winds, from the uttermost part of the earth to the uttermost part of heaven. And then shall he send his angels, and shall gather together his elect from the four winds, from the uttermost part of the earth to the uttermost part of heaven.
On the Mount of Olives the words were spoken in answer to Peter, James, John, and Andrew when they asked when the temple would be destroyed and what would be the sign of His coming and of the end of the world. The discourse mingles the destruction of Jerusalem with the final crisis, so the gathering of the elect concerns the great day of His coming and not Jerusalem alone. Words spoken of Jerusalem reach beyond that event to the final conflagration when the world is punished for iniquity.
The two events were blended in mercy because the disciples could not have endured the future as beheld, leaving them to study out the meaning for themselves. The discourse was given not for the disciples only but for those who live in the last scenes of this earth's history. The gathering of the elect takes place at the visible coming of the Son of man in the clouds with great power and glory, after the tribulation and after the signs and shaking of the powers of heaven in the sun, moon, stars, and heavenly powers.
The shaken powers are the sun, moon, and stars, which are moved out of their places by the voice of God but do not fall or pass away. At that coming He sends His angels with a trumpet call to bring together His chosen people from every quarter, from the four winds, from the uttermost part of the earth to the uttermost part of heaven. After this shaking, the Holy City comes down through an opening in the heavens.
The gathering is among the events showing His return is near, though the exact day and hour have not been revealed. Those who receive and obey the light will be prepared to meet Him when He returns to gather His people.