Joshua 16-17

“For you shall drive out the Canaanites, even though they have chariots of iron and though they are strong" (17:18).  God brought Abraham’s descendents into Canaan, just as He promised.  Yet God did not simply hand them the land based on the faith of their ancestors – not even Joseph’s descendents got a free ride (17:16).  Each new generation of Israelites faced some challenge, in this case, armed and fierce Canaanites. 

The God of their ancestors became their God when they acted in faith, believing He would defend, protect, and fight for them too.