God came down and suddenly, as the workers gathered for work one morning, they found they couldn’t communicate with each other anymore. The word “confusion” only begins to describe individuals’ personal terror, shock and isolation, and collapse of their society.
So the descendants of Noah’s plan to build a colossal ziggurat in order to storm the gates of heaven and take over was not a surprise for God, and it didn’t force Him to scramble for some sort of Plan B to rescue His purposes for the cosmos, or for humankind.
This sign was a reversal of God’s judgment at the Tower of Babel. God’s judgment scattered and separated those people then, now He was uniting His people in the Spirit. At Babel no one could understand anyone else, but at Pentecost everyone could understand and hear God’s praises.