Joshua 11

For it was of the Lord to harden their hearts, that they should come against Israel in battle, that He might utterly destroy them, and that they might receive no mercy, but that He might destroy them, as the Lord had commanded Moses. v.20

Read chapter 11
I know, I know.  Seems like God is such a horrible god when you read this verse that He hardened their hearts and utterly destroyed them showing no mercy.  Where's the merciful, loving God in this occurrence?  Well we can understand this wording that is similar to other areas of scripture, like the harding of Pharaoh's heart in Exodus 4 & 7.  What is more than taking this one verse out of the whole is that these nations that Israel was destroying by the hand of God were peoples who had were acting continually contrary to the Divine will of God. "It was the design of God’s providence not to soften their hearts to a compliance with the Israelites, but to give them up to their own animosity, pride, confidence, and stubbornness" as Matthew Henry puts it. God was giving them over to themselves that their free will chose.  The Lord hardening their hearts is just the culmination of where their free will led them to be destroyed.  Not everyone comes to God like the Gibeonites  came to Joshua (see Joshua 9) to ask to be spared.  God knows their hearts if they would believe the signs or not and gave them up to that.  We can't just imagine this cold blooded killing, but perhaps more-so a swift destruction as we see how quickly the land was conqured and given to the Israelites.  How do you take and understand passages like these?