The last words Jesus said before physically lifting off from planet earth were, "But you will receive power when the Holy Spirit comes on you; and you will be my witnesses in Jerusalem, and in all Judea and Samaria, and to the ends of the earth." (Acts 1:8). That statement sets the theme for the whole of Acts. The book describes how the Holy Spirit empowered the apostles and other believers to spread the message that Jesus is alive and able to save all who trust in Him (Acts 4:8-12).

But before the Holy Spirit could be given to Christ's new church, Jesus had to return to heaven (John 16:7). The disciples should not have been surprised when Jesus' feet left the ground and He ascended into the sky until He was hidden by a cloud. But they were because they did not yet have the Holy Spirit within them to interpret what they were seeing in the light of what Jesus had said. 40 days previously they had the same difficulty in understanding the resurrection, although Jesus had repeatedly told them what to expect (Luke 18:31-34). And so angels appeared again, as they had at the tomb (Luke 24:4-7), to explain this unique event.

Christ's departure and His Second Coming will be similar. Jesus will appear physically in the sky, coming through clouds (Matthew 24:30-31). He will be instantly identifiable. There will be no doubt that the King has come to reign. That day will mark the end of gospel opportunity: those who love Him, and those who do not, will rejoice and mourn respectively (Revelation 1:7). That is the great Day of the Lord when His supremacy will not be denied by anybody; every knee will bow (Philippians 2:9) as the King is revealed in His glory (1 Thessalonians 4:16-17).

We live in the time gap between Jesus' ascension and return. Like the apostles, we are called to be witnesses of the grace of Christ. We are to grow a character like His (Galatians 5:22-25) and tell the truth about His mission to save all human beings from God's wrath against sin (Matthew 28:18-20). We are to love like Him, living with His strength and courage in a wicked world by the Spirit's power; explaining the gospel winsomely so that the message is understood, encouraging people to respond in repentance and faith. That is the story in the Acts of the Apostles: that should be our story too. It may be a challenge, but it is the life purpose of every believer. We do not know when He will return, but until then we have His work to do (Luke 19:13).