What if man did establish a lasting world peace? What would be accomplished by this? Yes, it would be great on the surface to live on earth in peace, but what would be the long term effect? Answer: more sin, more rebellion, more infidelity, more atheism, and more apostasy! Men don't seek God during peaceful times. It is during such times that men pursue their carnal and selfish dreams. It is during such times that churches fall into apostasy. War, hardship, and persecution tend to bring out the best in people, while peace and prosperity do just the opposite.
Furthermore, if man were to bring about world peace, God would be declared a liar, and all the false "peace prophets" would be looked upon with admiration. Consider Jeremiah 14:13-15:"Then said I, Ah, Lord GOD! behold, the prophets say unto them, Ye shall not see the sword, neither shall ye have famine; but I will give you assured peace in this place. Then the LORD said unto me, The prophets prophesy lies in my name: I sent them not, neither have I commanded them, neither spake unto them: they prophesy unto you a false vision and divination, and a thing of nought, and the deceit of their heart. Therefore thus saith the LORD concerning the prophets that prophesy in my name, and I sent them not, yet they say, Sword and famine shall not be in this land; By sword and famine shall those prophets be consumed." And let's not forget what the Lord Jesus said in Matthew 24:6-7: "And ye shall hear of wars and rumours of wars: see that ye be not troubled: for all these things must come to pass, but the end is not yet. For nation shall rise against nation, and kingdom against kingdom: and there shall be famines, and pestilences, and earthquakes, in divers places." Liberal preachers throughout our land have been preaching peace for decades. These preachers have very liberal views concerning the deity of Christ, the virgin birth, the blood atonement, the bodily resurrection, the literal second coming, the reality of hell, the authority of God's word (KJV), the autonomy of the local church and a whole lot more. If their prophesies of world peace were to come true, then Jesus Christ would be discredited, less people would believe the Bible than ever, and true Bible believers would be less believable than ever. The philosophy of the world would be, "You see! Man isn't that bad after all!"
God said that man is bad, and God said that there will be no world peace. Isaiah 57:20-21 says, "But the wicked are like the troubled sea, when it cannot rest, whose waters cast up mire and dirt. There is no peace, saith my God, to the wicked." They CANNOT REST, and they CANNOT HAVE PEACE.