The Mosaic Covenant is a conditional covenant made between God and the nation of Israel at Mount Sinai (Exodus 19-24). It is sometimes called the Sinai Covenant but is more often referred to as the Mosaic Covenant since Moses was God’s chosen leader of Israel at that time. The pattern of the covenant is very similar to other ancient covenants of that time because it is between a sovereign king (God) and his people or subjects (Israel). At the time of the covenant, God reminded the people of their obligation to be obedient to His law (Exodus 19:5), and the people agreed to the covenant when they said, “All that the Lord has spoken we will do!” (Exodus 19:8). This covenant would serve to set the nation of Israel apart from all other nations as God’s chosen people and was as equally binding as the unconditional covenant that God made with Abraham because it is also a blood covenant. The Mosaic Covenant is a significant covenant in both God’s redemptive history and in the history of the nation of Israel through whom God would sovereignly chose to bless the world with both His written Word and the Living Word, Jesus Christ.
The Mosaic Covenant was centered around God’s giving His divine law to Moses on Mount Sinai. In understanding the different covenants in the Bible and their relationship with one another, it is important to understand that the Mosaic Covenant differs significantly from the Abrahamic Covenant and later biblical covenants because it is conditional in that the blessings that God promises are directly related to Israel’s obedience to the Mosaic Law. If Israel is obedient, then God will bless them, but if they disobey, then God will punish them. The blessings and curses that are associated with this conditional covenant are found in detail in Deuteronomy 28. The other covenants found in the Bible are unilateral covenants of promise, in which God binds Himself to do what He promised, regardless of what the recipients of the promises might do. On the other hand the Mosaic Covenant is a bilateral agreement, which specifies the obligations of both parties to the covenant.
The Mosaic Covenant is especially significant because in it God promises to make Israel “a kingdom of priests and a holy nation” (Exodus 19:6). Israel was to be God’s light to the dark world around them. They were to be a separate and called-out nation so that everyone around them would know that they worshiped Yahweh, the covenant-keeping God. It is significant because it is here that Israel received the Mosaic Law that was to be a schoolmaster pointing the way towards the coming of Christ (Galatians 3:24-25). The Mosaic Law would reveal to people their sinfulness and their need for a Savior, and it is the Mosaic Law that Christ Himself said that He did not come to abolish but to fulfill. This is an important point because some people get confused by thinking that keeping the Law saved people in the Old Testament, but the Bible is clear that salvation has always been by faith alone, and the promise of salvation by faith that God had made to Abraham as part of the Abrahamic Covenant still remained in effect (Galatians 3:16-18).
Also, the sacrificial system of the Mosaic Covenant did not really take away sins (Hebrews 10:1-4); it simply foreshadowed the bearing of sin by Christ, the perfect high priest Who was also the perfect sacrifice (Hebrews 9:11-28). Therefore, the Mosaic Covenant itself, with all its detailed laws, could not save people. It is not that there was any problem with the Law itself, for the Law is perfect and was given by a holy God, but the Law had no power to give people new life, and the people were not able to obey the Law perfectly (Galatians 3:21).
The Mosaic Covenant is also referred to as the Old Covenant (2 Corinthians 3:14; Hebrews 8:6, 13) and was replaced by the New Covenant in Christ (Luke 22:20; 1 Corinthians 11:25; 2 Corinthians 3:6; Hebrews 8:8; 8:13; 9:15; 12:24). The New Covenant in Christ is far better than the old Mosaic Covenant that it replaces because it fulfills the promises made in Jeremiah 31:31-34, as quoted in Hebrews 8.