What did God plan to do with the Canaanites so Israel could take the land?
God planned to remove the Canaanite population, using hornets or whatever means necessary, while leaving everything intact. Israel was simply to walk in and take over the land under God's blessings. Their first step of unbelief was requesting spies, though God's original instruction was to go in and take it.
Les explains that God had a system to literally remove the Canaanite population while leaving everything intact, so all Israel had to do was walk in and take over with God's blessings. He compares it to a bomb that kills people but leaves things intact, perhaps a neutron bomb, and notes God was way ahead of them. God said He would use hornets or whatever to drive the Canaanites out. Because of unbelief, they didn't do it. Instead of going in directly, they asked to send spies, and God condescended to that. If the spies had returned with a positive report and they had gone in, God would have let them; it was a valid offer. Les emphasizes that unbelief was the reason they failed, and unbelief is the cause of eternal punishment, though the determination of punishment is according to works.