How do we know God does not fail in His promises?

The affirmation in Joshua that not one of the Lord's promises failed reinforces the doctrine of God's unchanging nature and trustworthiness. Even though the Israelites often struggled to believe in God’s promises, the fulfillment of those promises serves as a profound comfort. The record in Joshua assures us that God’s sovereignty and faithfulness are paramount; His plan cannot be thwarted by human weakness. This understanding is central to historic Reformed theology, which emphasizes God's control over all aspects of creation, including redemptive history.