Before the Israelites turned their attention to Jericho, God directed Joshua to perform the covenant renewal ceremony of circumcising all the males born in the forty years since the exodus from Egypt. Because the land was part of the covenant promise, Israel’s men needed to demonstrate their personal participation in the covenant through circumcision in order to enter into the land.
Flint occurs in nature without human shaping. For this reason, people used flint knives for circumcision as a symbol of purity and holiness.