What does Judges 6:38 mean?

Gideon is having doubts about whether God truly plans to rescue Israel—from the swarming Midianites and their allies (Judges 6:1–5) through him (Judges 6:15–16). Despite all God has already shown Gideon, he wants even more evidence that all this is true. It's easy to be brave when reading about battle, and not participating in it; readers should temper judgment by remembering that Gideon is not a soldier. All the same, he's already witnessed God's miraculous power and intervention (Judges 6:19–21; 25–32; 34–35). To not only ask for more proof, but to insist on something so specific, is an expression of unreasonable doubt. At the same time, Gideon's request expresses a sensible understanding of God's power over nature.

The test which Gideon devised involves something naturally impossible: that a furry animal skin, left outside overnight, to be soaked with dew while the ground around it is dry (Judges 6:37). If the wool is wet while the ground is dry the next morning, Gideon will take this as a sign that God still plans to do all He has said.

This verse sums up the result with "and it was so." In fact, God makes the miracle obvious: Gideon awakes to find an animal skin so wet that Gideon fills a bowl wringing it out. One would think this has Gideon convinced—but he's not. In an almost-unbelievable level of skepticism, he asks God to invert the same miracle before he fully trusts (Judges 6:39).