“they will gather together his chosen ones.” In this context, the “chosen ones” are the sheep of the Sheep and Goat Judgment, and also likely the people of the first resurrection, the resurrection of the righteous, who come up out of the graves and are brought back to the land of Israel (Ezek. 37:12-14).
In the future there will be a time of great tribulation; a time of terrible destruction and death. The Old Testament prophets spoke of it often (see commentary on Dan. 12:1), Jesus Christ taught about it (Matt. 24, Mark 13, Luke 21) and it is described in some detail in the Book of Revelation, which says there will be seal judgments, trumpet judgments, thunder judgments, and bowl judgments. That time of great tribulation will end when Jesus Christ comes down to earth and fights the Battle of Armageddon and conquers the earth (Rev. 19:11-21). Then Jesus will set up his 1,000-year kingdom on earth. Christ’s kingdom on earth will include Christians, who were in the Rapture, the people who are in the first resurrection (Rev. 20:1-5), and the “sheep” of the Sheep and Goat Judgment (Matt. 25:31-46).
When Christ conquers the earth he will send out his angels who will gather the people who survived the Tribulation and Armageddon. Those survivors will be divided into two groups, the “sheep” and the “goats,” and the sheep will be allowed to enter the Millennial Kingdom of Jesus Christ (the “sheep” of Matt. 25:31-46 are also the “wheat” of Matt. 13:24-30, 36-43). The “sheep” who are gathered are part of the “chosen” who are gathered in Matt. 24:31 Also, however, the Old Testament says that when the people get up from the grave in the first resurrection, they have to be brought back to Israel, so it is likely that here in Matthew 24:13, the “chosen” who are gathered also include both the “sheep” and the righteous people who are in the resurrection of the righteous, the first resurrection. Other scriptures also speak of Jesus coming with his angels when he comes to earth (Matt. 13:41; 16:27; 24:31; 25:31; Mark 8:38; 13:27; Luke 9:26).
[For more on the Sheep and Goat Judgment, see commentary on Matt. 25:32 and 25:33. For more about Jesus’ future kingdom on earth, see Appendix 3, “Christ’s Future Kingdom on Earth”].