There are five reasons why Christ has to return:
(1) - Jesus must come back because of the promises of the Old Testament that have yet to be fulfilled. Scores of prophecies were fulfilled concerning His First Coming. But some prophecies still remain to be fulfilled. For example, the Scripture says, "The government shall be upon his shoulder. ... Of the increase of his government and peace there shall be no end, upon the throne of David, and upon his kingdom, to order it, and to establish it with judgment and with justice from henceforth even for ever."(Isaiah 9:6-7)
That Scripture has not been fulfilled. The government is not yet upon His shoulder. Jesus did not bring world peace in His First Coming, nor did He bring world justice. But He will bring it the second time, because the Scripture teaches that all prophecies will be fulfilled. (Ezekiel 12:23-28).
In Micah the prophet says, "They shall beat their swords into plowshares, and their spears into pruninghooks: nation shall not lift up a sword against nation, neither shall they learn war any more."(Micah 4:3) Consider the wars that are being fought now. Some day, however, people will make spears into pruninghooks, and nations will not lift up swords against nations. Why? Because the Prince of Peace is coming back--He's going to be the world ruler.
*(2) - Jesus Christ has to return because of His own statements. He is absolute truth. The Bible says, "For as the lightning cometh out of the east, and shineth even unto the west; so shall also the coming of the Son of man be."(Matthew 24:27) This prophecy has yet to be fulfilled, but I believe it will be, because He said it.
Jesus didn't lie to us. He said, "I go to prepare a place for you. And if I go and prepare a place for you, I will come again, and receive you unto myself; that where I am, there ye may be also."(John 14:2-3) The Lord Jesus Himself is coming back! That's how much He loves us. He gives us a new life here, but He also has a great plan for the future. For eternity!
The Bible says that we are joint heirs with the Lord Jesus Christ and that we will spend eternity with Him. What is He doing now? He is preparing a home for us who love Him. It has been 2,000 years. What a home it must be!
*(3) - Jesus Christ must come back because of the present position of Satan. The devil is the most powerful being in all the world, except for God Himself. The Bible says that the devil is called "the god of this world."(2Corinthians 4:4) That means that he's the director of the false religions and philosophies of the world. Humanity is helpless before him. Mankind is unable to chain him. The churches cannot dethrone him. Legislation is impotent in dealing with the enormous power of evil in the world.
But let's not forget one fact. There is One who is more powerful than Satan is.This One defeated Satan 2,000 years ago on the cross. Satan suffered his greatest defeat at the cross and in the resurrection of the Lord Jesus Christ.
But the devil is still loose, still in charge of the evil that is in the world: All the injustices, all the wars, all the crime, all the wickedness, all the terrible things, in the world.
There's only one Person in heaven or on earth who can deal with the devil, and He's coming back to throw Satan into the bottomless pit and ultimately into the lake of fire. Then we will be freed from this terrible pull of evil and the satanic power that has controlled the hearts of people for all these centuries. That's why Christ has to come. He's the only One who can deliver us. And the world is looking for a deliverer.
*(4) - Jesus Christ must return because of the present chaos in the world--our world is racked with pain, suffering, hunger, war, murder, lust, greed, hate, fraud, corruption. Human government seems to be unsuccessful in dealing with these problems. The world is becoming more and more helpless and hopeless in this technological age. Many sociologists and scientists believe we have the capability to destroy ourselves. And we can.
But the Scripture says, "Say to them that are of a fearful heart, Be strong, fear not: behold, your God will come with vengeance, even God with a recompense; he will come and save you."(Isaiah 35:4) Jesus Christ will save us and set up His Kingdom of righteousness and glory and peace and justice. And what a world that's going to be! Will you be ready?
*(5) - Jesus Christ must come back because of the dead in Christ--those people who died believing in God and trusting Him. When Jesus comes back, there will be a great resurrection and the believers will be raised from the dead, and the believers who are alive will be caught up in the air to be with the Lord. (1 Thessalonians 4:16-17)