"Now when He had spoken these things, while they watched, He was taken up, and a cloud received Him out of their sight. And while they looked steadfastly toward heaven as He went up, behold, two men stood by them in white apparel, who also said, 'Men of Galilee, why do you stand gazing up into heaven? This same Jesus, who was taken up from you into heaven, will so come in like manner as you saw Him go into heaven.'" —Acts 1:9-11 Other signs:
- The coming of Christ will be instantaneous and worldwide. "For as the lightning comes from the east and flashes to the west, so also will the coming of the Son of Man be."—Matthew 24:27
- The coming of Christ will be visible to all. "Then the sign of the Son of Man will appear in heaven, and then all the tribes of the earth will mourn, and they will see the Son of Man coming on the clouds of heaven with power and great glory." —Matthew 24:30
- The coming of Christ will be audible. "And He will send His angels with a great sound of a trumpet, and they will gather together His elect from the four winds, from one end of heaven to the other."—Matthew 24:31
- The resurrection of the righteous will occur. "For the Lord Himself will descend from heaven with a shout, with the voice of the archangel, and with the trumpet of God. And the dead in Christ will rise first."—1 Thessalonians 4:16
- In one single event, the saved who are alive at Christ's coming will be caught up together with the resurrected to meet the Lord in the air. "Then we who are alive and remain shall be caught up together with them in the clouds to meet the Lord in the air. And thus we shall always be with the Lord."—1 Thessalonians 4:17 (Above arrangement of scriptures/comments are mostly from Wikipedia online 6/2013)
Please note that the Coming of Jesus Christ is compared to the times of Noah. For it says in Matthew 24:37-39, "But as the days of Noe were, so shall also the coming of the Son of man be. For as in the days that were before the flood they were eating and drinking, marrying and giving in marriage, until the day that Noe entered into the ark, and knew not until the flood came, and took them all away; so shall also the coming of the Son of man be." (KJV) This is also consistent with the concept that as Jesus Christ will come to judge all those on the entire earth, so did God judge all those on the entire earth in the time of Noah with a worldwide Flood.
It is time to Repent:
22 So Paul stood in the midst of the Areopagus and said, “Men of Athens, I see that you are very religious in all respects.
23 For while I was passing through and examining the objects of your worship, I also found an altar with this inscription, ‘TO AN UNKNOWN GOD.’ Therefore, what you worship in ignorance, this I proclaim to you.
24 The God who made the world and everything that is in it, since He is Lord of heaven and earth, does not dwell in temples made by hands;
25 nor is He served by human hands, as though He needed anything, since He Himself gives to all people life and breath and all things;
26 and He made from one man every nation of mankind to live on all the face of the earth, having determined their appointed times and the boundaries of their habitation,
27 that they would seek God, if perhaps they might feel around for Him and find Him, though He is not far from each one of us;
28 for in Him we live and move and exist, as even some of your own poets have said, ‘For we also are His descendants.’
29 Therefore, since we are the descendants of God, we ought not to think that the Divine Nature is like gold or silver or stone, an image formed by human skill and thought.
30 So having overlooked the times of ignorance, God is now proclaiming to mankind that all people everywhere are to repent,
31 because He has set a day on which He will judge the world in righteousness through a Man whom He has appointed, having furnished proof to all people by raising Him from the dead.”