Covenants in the Old Testament
The Bible has a lot to say about covenants. Throughout the Bible, various covenants are mentioned. Covenant theologians study the biblical data in order to explain the purpose, the unique characteristics, and the relationships between the covenants. A covenant, generally defined, is a bond that binds two parties together. Besides some references to covenants between people or nations (e.g., Gen. 26:28-29), and covenant language regarding creation (e.g., Jer. 33:25), the Bible usually mentions covenant in the context of the relationship between God and people. We distinguish between the covenant of works (see e.g., Hos. 6:7), the covenant of redemption (implied in many passages), and the covenant of grace. Most often when the Bible mentions a “covenant,” it refers to the covenant of grace.
Through his disobedience, Adam broke the covenant of works for himself and all his descendants (Rom. 5:12-13). The result was death – both physical and spiritual – for Adam and his posterity (cf. Rom. 3:23; Eph. 2:1-10). Without cancelling His original covenant with Adam, God immediately proceeded to declare war on the serpent and his seed. In this declaration, God announced something that would take the rest of the Bible to unfold, that is, that there was to be another covenant besides the covenant of works, this time a covenant of grace. The covenant of grace would be a binding agreement involving promises, made in the shed blood of Jesus Christ. It would be undertaken from God's side and extend to sinners, lost and undone. Since God's grace, not human works, is central to this covenant, God would call sinners to repentance and faith, and through them and their seed, this covenant would extend throughout the world, and bring a full yield of saved sinners, who will praise God throughout endless ages.
When we read the OT, we see that a lot of time passes between Adam's fall in Genesis 3 and Jesus' coming in the NT. Why did it take so long? What was God doing? God was progressively unfolding the covenant of grace throughout history. God did not simply come in Genesis 3 and fully manifest His plan of redemption. Rather, God slowly and gradually revealed to man how He would redeem lost sinners by the work of Christ in successive covenants made throughout the OT. Covenant theology chiefly identifies four such covenants in the OT and prophesies one that will be confirmed in the shedding of Christ's blood. These four covenants are often called the Noahic, Abrahamic, Mosaic, and Davidic (respectively titled after the people with whom God used to reveal his plan of redemption). These are not separate covenants, but four administrations of the covenant of grace.
The Noahic covenant (Genesis 6-9) is a covenant that focuses on God's ultimate plan of restoring the earth. It gives shape to the original promise regarding the seed of the woman. It shows how this promise will run through the line of Shem. As God unfolds the grace and life that He will bring in the covenant, He promises to never flood the earth again. As a sign that He will keep His promise, He places His multi-colored bow in the sky, pointing heavenwards.
The Abrahamic covenant (Genesis 12, 15, 17) is a covenant that focuses on God's calling a seed and graciously providing for them everything that they need. These blessings flow out of the redemption that is set forth in the types and shadows of altars and the blood of animals, pointing to Christ. This redemption is applied to Abraham by faith in justification (Gen. 15:6). In a covenantal ceremony (see Gen. 15), God walks between the halves of cut-up animals, sealing to Abraham how He will fulfill His seven-fold promise to Abraham (Gen. 12:1-3). In this way, God shows that what man could never do, God will do. Out of His divine grace He freely promises these things to Abraham. When Abraham “believed” God, it was reckoned to him as righteousness by faith (Gen. 15:6, faith being the instrument through which believers are accepted as righteous before the just judgment of God). This had implications for the descendants of Abraham (Gen. 17:7), for God made clear that He promised to be their God as well, in their generations. It also had implications for how Abraham should raise his seed (Gen. 18:19).
The Mosaic covenant (Exod. 19-23; Deut. 5) had a national dimension. Instead of being limited to Abraham and his family, the scope of the covenant was widened to all who were Israelites. God constituted the Israelites as His holy nation, calling them out of bondage (see Exod. 20:1). God multiplied His dealings with Abraham's descendants by now redeeming them as a people. The moral law was given at Horeb, not as a renewed covenant of works, but as a rule to walk in thankfulness and holiness in light of the deliverance from bondage. Notwithstanding, this period was characterized by strictness and a measure of darkness (see Gal. 3:24; Heb. 12:18-21). For example, any person or animal who touched Mount Sinai was to be put to death. In this administration of the covenant of grace, God intended to prepare for a freedom and radiance under the new covenant after the death and resurrection of Christ.
In the Davidic covenant (2 Sam. 7) God promised to build a house, or an everlasting kingdom, for David, and that David's Son would rule on the throne of Israel. In this particular covenant God was pointing to the ultimate Seed of the woman, who would crush Satan's head and bring in the everlasting kingdom of grace and glory.
Towards the end of the Old Testament, the prophets began to mention a new administration of the covenant, the new covenant (Jer. 31:31-34). It would not differ in essence from the old covenant, but it would bring certain 'new' benefits, as we will see in our next section.