Just like many prophecies about Jesus about his first arrival...there are hundreds, which prove that Jesus was who he said he was, the bible also talks about Jesus' second coming. It's been foretold in the bible and it will happen, even though we don't know when. It's the ultimate hope Christians have.
With his coming, there are several promises.
"For the Son of Man will come in the glory of His Father with His angels, and then He will reward each according to his works. Matthew 16:27 (NKJV)
"For whoever is ashamed of Me and My words, of him the Son of Man will be ashamed when He comes in His own glory, and in His Father's, and of the holy angels. Luke 9:26 (NKJV)
"But of that day and hour no one knows, not even the angels of heaven, but My Father only. "But as the days of Noah were, so also will the coming of the Son of Man be. "For as in the days before the flood, they were eating and drinking, marrying and giving in marriage, until the day that Noah entered the ark, "and did not know until the flood came and took them all away, so also will the coming of the Son of Man be. "Then two men will be in the field: one will be taken and the other left. "Two women will be grinding at the mill: one will be taken and the other left. "Watch therefore, for you do not know what hour your Lord is coming. Matthew 24:36-42 (NKJV)
"It is like a man going to a far country, who left his house and gave authority to his servants, and to each his work, and commanded the doorkeeper to watch. "Watch therefore, for you do not know when the master of the house is coming--in the evening, at midnight, at the crowing of the rooster, or in the morning- "lest, coming suddenly, he find you sleeping. Mark 13:34-36 (NKJV)
"But take heed to yourselves, lest your hearts be weighed down with carousing, drunkenness, and cares of this life, and that Day come on you unexpectedly. "For it will come as a snare on all those who dwell on the face of the whole earth. "Watch therefore, and pray always that you may be counted worthy to escape all these things that will come to pass, and to stand before the Son of Man." Luke 21:34-36 (NKJV)
For this we say to you by the word of the Lord, that we who are alive and remain until the coming of the Lord will by no means precede those who are asleep. For the Lord Himself will descend from heaven with a shout, with the voice of an archangel, and with the trumpet of God. And the dead in Christ will rise first. 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. Therefore comfort one another with these words. 1 Thessalonians 4:15-18 (NKJV)
For you yourselves know perfectly that the day of the Lord so comes as a thief in the night. For when they say, "Peace and safety!" then sudden destruction comes upon them, as labor pains upon a pregnant woman. And they shall not escape. 1 Thessalonians 5:2-3 (NKJV)
"And behold, I am coming quickly, and My reward is with Me, to give to every one according to his work. Revelation 22:12 (NKJV)
He who testifies to these things says, "Surely I am coming quickly." Amen. Even so, come, Lord Jesus! Revelation 22:20 (NKJV)