Some skeptics think that Judges 1:19 contradicts Luke 1:37, “For with God nothing will be impossible.” It was Judah, not God, who could not drive out the inhabitants of the valley. The assumption is that because God was with Judah, they were therefore promised victory over their enemies. This is clearly a faulty deduction. It is true that nothing is impossible with God and that He was with Judah, but the problem was their disobedience. Even though they had earlier been assured of victory against their enemies with iron chariots (Josh. 17:18), they apparently became fearful and failed to trust God to give them victory. God is with the believer; nothing is impossible for Him to accomplish through those who obey Him. There is no contradiction.
Judges 1:19 So the Lord was with Judah. And they drove out the mountaineers, but they could not drive out the inhabitants of the lowland, because they had chariots of iron.