Deuteronomy has a sermonic character. It may be best to consider Deuteronomy as Moses’ messages to Israel as they prepared to enter Canaan—exhortations based upon the events and instruction recorded in Genesis-Numbers.
Moses’ theme in the opening chapters of Deuteronomy is one of covenant faithfulness. In the first three chapters of Deuteronomy, Moses reminded Israel of God’s covenant faithfulness to them. Moses wished for Israel to be mindful of the land-promise of the Abrahamic covenant (Deut 1:6-8) and how God provided judges who would apply Torah to Israel’s new situation in Canaan (Deut 1:9-18; see Exodus 18). Moses reminded the people that when their ancestors initially failed to take the land at Kadesh Barnea, God was faithful to recompense justly both the unbelieving and the faithful that remained among them (Deut 1:19-46). God displayed His faithfulness during Israel’s journey through the southern Transjordan (Deut 2:1-23) and their initial conquest of the regions to the north. There Israel defeated Sihon and the Amorites as well as Og and the people of Bashan (Deut 2:24-3:7). This territory was allotted to the tribes of Rueben, Gad, and East Manasseh (Deut 3:8-20). Israel enjoyed the promise of God’s faithfulness in the change of leadership from Moses to Joshua (Deut 3:21-29).
In Deuteronomy 4, Moses called Israel to respond to God with their whole heart. Moses emphasized the demand for Israel to be faithful to the covenant stipulations—so that they would possess the land (Deut 4:1-4) and be a witness to the surrounding nations. Israel’s life in Canaan was to be a witness of the true God (Deut 4:1-8). Moses cast a vision for future generations in Israel to know of God’s covenant faithfulness to His people (Deut 4:9-14)—that they would continue to revere His holiness (Deut 4:15-40) and maintain integrity in the land (vv. 41-43).
Moses’ message at the outset of Deuteronomy casts a shadow into the New Testament. The covenant ceremony at Mount Sinai—including the black cloud, blazing fire, and frightening presence of the Lord (Deut 4:10-14; see Exod 19:10-19)—proved to be a distinctly different experience than what the author of Hebrews understood to be the case for his readers. While Israel’s covenant emphasized the distance between the Lord and His people, the new covenant is based upon the fact that Jesus took on flesh to fully identify with His own. The author of Hebrews wrote that God’s drawing near to humanity in Jesus provides access for believers to draw near to God. The author reminded his audience that they had not come to God’s fearful presence at Mount Sinai where the people were forced to remain at a distance. “Instead,” he said, “you have come to Mount Zion, to the city of the living God (the heavenly Jerusalem), to myriads of angels in festive gathering, to the assembly of the firstborn whose names have been written in heaven, to God who is the judge of all, to the spirits of righteous people made perfect, to Jesus (mediator of a new covenant)” (Heb 12:22-24a). Moses was concerned that Israel remember God’s holiness displayed on Mount Horeb and avoid idolatry. “For the LORD your God is a consuming fire, a jealous God,” Moses said (Deut 4:24). The author of Hebrews took up Moses’ line, applying it in light of the access his audience enjoyed with God through Jesus Christ and the reality of the unshakable kingdom of the new covenant: “Therefore, since we are receiving a kingdom that cannot be shaken, let us hold on to grace. By it, we may serve God acceptably, with reverence and awe; for our God is a consuming fire” (Heb 12:28-29).