One thing that keeps popping up in our OT passage is that there were numerous areas where the Israelites had not driven out the people of the land. This failure to obey God and completely remove the pagan people and their gods would cause many problems for the nation in the future.
Are we guilty of the same? We are to root out every sin in our lives. There are no "safe" sins. Any sin allowed to remain in our lives will cause problems for us down the road. We cannot trivialize or make excuses for our sin.
Our NT passage makes it clear that judgement for sin will come at a time when no one expects it. People often mistake God's grace and delay of judgment to mean that judgment is never coming. It is coming, there is no doubt. We should recognize God's patience for what it is, an opportunity to repent before the judgment comes, when it will be too late.
Tomorrow's Bible In a Year Passage passage: Joshua 19-21; Luke 18:1-23