Questions and Answers

Is God all powerful or not?

This is obviously not a contradiction. The critic is reading the verse as saying that the LORD ... he ... could not drive out the inhabitants of the valley. The "he" is Judah, not the LORD.

God is all powerful

Jeremiah 32:27 - I am the LORD, is anything too hard for me?
Matthew 19:26 - With God all things are possible

God is not all powerful

Judges 1:19 - LORD was with the men of Judah. They were unable to drive the people from the plains.