King Nebuchadnezzar said, "and who is that God that will deliver you out of my hands?" The swift answer was, "...our God whom we serve..." So, now, the scene was set. They would either die in the fiery furnace for refusing to worship the golden image and its gods or they would be saved by their God, the God of Israel. We all know what happened. When Nebuchadnezzar went to check on them, they were walking in the fire talking to a fourth person. The fourth person turns out to be the Son of God.
Nebuchadnezzar becomes a believer and he does real good for awhile. Then, he gets to thinking that all of Babylon is great only because of his power and glory. God, our sovereign God, the governor among the nations (Psalm 22:28), sent a dream to Nebuchadnezzar telling him what was going to happen. Less than a year after the dream he went crazy. He finally came to himself and resumed praising God. (Daniel chapters 3 and 4)
Twenty-three years later while Belshazzar is king of Babylon the unthinkable happens. The Medes and the Persians are camped outside Babylon. Babylon, which has not been invaded for 1,000 years, is swiftly coming to its' end. Belshazzar who knew the story of Nebuchadnezzar and the God of Israel, believes he is invincible. He calls for the most sacred vessels from Solomon's temple to be used at a great party. These are the vessels that God has blessed and are sacred. No wonder that during the party, he is brought up short by a finger writing on the wall from out of nowhere.
God has paid him a visit. Belshazzar doesn't know the meaning of what is written and calls for Daniel to interpret the words. To sum it up, this is the final insult. He knew the story of Nebuchadnezzar. He knew that God "hath done whatsoever he hath pleased." (Psalm 115:3) He paid the final price for his disrespect for the Almighty God--he died that night. And Babylon fell.