The promise was clear:
For you shall drive out the Canaanites, though they have chariots of iron, and though they are strong. (Joshua 17:18)
But the people faltered:
And the LORD was with Judah, and they took possession of the hill country, but they could not drive out the inhabitants of the valley because they had iron chariots. (Judges 1:19)
One of the reasons we compromise when tempted is that not compromising feels too hard. We don’t want to work at overcoming temptation, if by work we mean anything other than tossing up a God-help-me prayer, followed by hoping that the enticement evaporates immediately. Judah likely made the same error when seeking to drive out the inhabitants of the plain: Those iron chariots are too hard to deal with.
The Lord would have propelled Judah to victory had they trusted his promise and pressed hard. Let’s learn from their mistake.