Promise Amidst Tribulation. 24 “But in those days after that tribulation the sun will be darkened, and the moon will not give its light, 25 and the stars will be falling from the sky, and the powers in the heavens will be shaken. 26 And then they will see ‘the Son of Man coming in the clouds’ with great power and glory, 27 and then he will send out the angels and gather (his) elect from the four winds, from the end of the earth to the end of the sky.
As noted in most outlines, we are jumping into the middle of Mark’s “Oliver Discourse.” Pheme Perkins  nicely locates it for us: “Both of the previous sections end with a note of warning to the elect: Persecution requires endurance (v. 13); the presence of false messiahs requires careful attention to the prophecies in the discourse (v. 23). Both sections also assure the faithful that they will be among the elect (vv. 13b, 20b). Thus each unit of prophetic discourse directs the reader’s attention from the present or impending historical experiences of persecution to the culmination of all things at the end time. The faithful testimony of Jesus’ disciples before human courts will assure them that the Son of Man will testify on their behalf in the heavenly court (13:9–13 echoes 8:34–38). A prophecy concerning the coming of the Son of Man to gather the elect now makes explicit the expectations built up in the previous sections.”
The opening verse of this Gospel could not offer words more closely associated with the “end time” so popularized in modern Christian fiction (e.g., the “Left Behind” series). Mark borrows these images from Old Testament prophet Daniel (Dan 7). But these same images are also found throughout the prophets (Isa 13:10; 34:4; Ezek 32:7–8; Joel 2:10–11; 3:4, 15), where a divine theophany causes the turmoil in nature. As Stoffregen notes “such phenomena have always been with us: solar and lunar eclipses, falling stars, booming thunder, etc. The time to prepare for the end has always been in the present time.” He notes that later in the discourse (vv.33,35), the imperatives: be watchful, be alert (blepete; agrypneite), and Watch (grygoreite) are present tense.
And while the discourse holds up somewhat terrifying images, what is promised is that the Son of Man will come together the elect from the ends of the Earth. His ascent to the divine throne marks the end of the war being waged by the fourth beast against the “holy ones.” God gives judgment on their behalf and bestows an everlasting dominion upon them (Dan 7:18, 26–27)
The ingathering is described as gather (his) elect from the four winds, from the end of the earth to the end of the sky. William Lane [476-477] notes that there are likely very distinct messages being delivered by each description (four winds, end of the earth, end of the sky): “The first describes the loss of national unity by the elect people as a consequence of their infidelity to God; the second announces the salvation of Israel through a return to spiritual and national unity. The regathering of dispersed Israel is an essential and traditional theme of Jewish eschatological hope (e.g. Tobit 14:7, “all the children of Israel that are delivered in those days, remembering God in truth, shall be gathered together …”; cf. Psalms of Solomon 17:28). When Jesus touched upon this theme in the context of the eschatological discourse he reinterpreted Israel’s hope in a profound way. Until that time the Temple of Jerusalem had been the visible center for the gathering of the scattered chosen people. The destruction of the Temple, however, would not result in their permanent dispersement. On the contrary, it will be followed by the regathering of the new people of God around the Son of Man, that is, around Jesus. The counterpart to the destruction of Jerusalem and the sanctuary is the eschatological salvation of the elect. The remnant of Israel will recover their lost unity through Jesus, the triumphant Son of Man. To be gathered by the Son of Man is to participate in the eschatological community and to experience the messianic blessing.”