The following is an excerpt from The MacArthur New Testament Commentary on Acts 1:9-11.

And after He had said these things, He was lifted up while they were looking on, and a cloud received Him out of their sight. And as they were gazing intently into the sky while He was departing, behold, two men in white clothing stood beside them; and they also said, “Men of Galilee, why do you stand looking into the sky? This Jesus, who has been taken up from you into heaven, will come in just the same way as you have watched Him go into heaven.” (Acts 1:9–11)

The Lord Jesus Christ was about to depart for heaven to return to His former glory (cf. John 17:1–6). Before doing that, He left the apostles with a final, dramatic moment which provided powerful motivation for carrying on His work. To their amazement, He was lifted up while they were looking on, and a cloud received Him out of their sight (cf. vv. 2, 11, 22). Jesus, in His glorious resurrection body, left this world for the realm of heaven to take His place on the throne at God’s right hand. Back on the Mount of Olives (Luke 24:50), the shocked apostles were gazing intently into the sky while He was departing. To their further consternation, angels, described as two men in white clothing, suddenly appeared and stood beside them. Such angelic appearances were not unusual (Gen. 18:2; Josh. 5:13–15; Mark 16:5). Two of them confirm the promise of Christ’s return as true (cf. John 8:17). These angels asked the bewildered apostles, “Men of Galilee, why do you stand looking into the sky?” They are called men of Galilee since all the apostles (With the exception of the dead traitor Judas) were from that region. The angels’ question, “why do you stand looking into the sky?” indicates more than curiosity at the miracle. The word translated looking indicates a long gaze, in this case a transfixed look as if losing someone. The question, then, is a mild rebuke to the apostles. They were not losing Jesus, as they feared. Maybe some of them remembered the vision of Ezekiel, who saw the glory of God depart to heaven from Israel (Ezek. 10:18–19) and feared it was happening again.

The angels went on to say, “This Jesus, who has been taken up from you into heaven, will come in just the same way as you have watched Him go into heaven.” The promise of Zechariah 14:4 will come to pass, namely that the Messiah will return to the Mount of Olives. The angels stressed that this same Jesus whom they had watched ascend would one day return in just the same way as they had watched Him go into heaven. He will return in His glorified body, accompanied with clouds (cf. Dan. 7:13; Matt. 24:30; 26:64; Rev. 1:7; 14:14), just as at His ascension.

This becomes a compelling motive. No one knows when He will come, but everyone must live in anticipation that it could be in their lifetime (cf. Rom. 13:12–14; 2 Peter 3:14–18). The truth that Christ will return provides a powerful motive to serve Him. Paul writes, “We must all appear before the judgment seat of Christ, that each one may be recompensed for his deeds in the body, according to what he has done, whether good or bad” (2 Cor. 5:10). In Revelation 22:12 the Lord Jesus Christ said, “Behold, I am coming quickly, and My reward is with Me, to render to every man according to what he has done.” Believers must serve Christ faithfully in light of His imminent return. In Revelation 16:15 Jesus warned, “Behold, I am coming like a thief. Blessed is the one who stays awake and keeps his garments, lest he walk about naked and men see his shame” (cf. 1 John 2:28).

The task of finishing the work that Jesus began, the duty of evangelizing the lost world, is a daunting one. But the Lord in His mercy from the start has provided all the spiritual resources necessary to accomplish that task. It is up to each believer to appropriate those resources and put them to use. “We must work the works of Him who sent [Jesus Christ], as long as it is day; night is coming, when no man can work” (John 9:4).