What does Judges 3:5 mean?

This and the following verse conclude the second introduction to the book of Judges. These two verses reiterate how catastrophically Israel failed to obey the commands of the Lord after moving into the Promised Land. The first and most glaring problem is that they failed to obey God's command to drive out all the other inhabitants of the land. God explicitly told them not to allow the wicked, depraved Canaanite culture to persist (Deuteronomy 20:16–18). And yet, Israelites settled among the occupants of the land.

Those occupants—the cultures allowed to co-exist alongside Israel in the territories they captured—included the Canaanites, Hittites, Amorites, Perizzites, Hivites, and Jebusites. These are not precisely the same nations listed earlier (Judges 3:3). The prior nations are those living in unconquered territory, who would plague Israel with raids and military oppression. This verse lists the residents of Canaan who continue to exist within Israel's own borders, because the Israelites disobeyed God's direct commands to get rid of them.

God's warning to Israel was clear: that the Canaanites were deeply evil. The Lord intended to use Israel to bring about the Savior of the entire world (Luke 2:11; Genesis 12:3). A major reason God commanded a purging of the Promised Land was the combination of those two facts (Deuteronomy 7:1–5; 9:4–5). Casual readers might be confused as to why God seems so intensely concerned that Israel remove these people from the land. History tells us that Canaanite religion involved depraved practices like temple prostitution. They also participated in human and child sacrifice.

Had the Canaanites been eradicated from the Promised Land, they would not have become such a persistent negative influence on their loyalty to God (Judges 3:6).