From the beginning, God intended for humankind to be in a relationship with Himself. Adam and Eve enjoyed perfect communion with God in a sinless and perfect world while they lived in the Garden of Eden. Then one day, Adam and Eve chose to forsake their relationship with God to pursue their sin. This tragic day had severe relational consequences for them and for us as their descendants.

Thankfully, God did not abandon His relationship with humanity. He has repeatedly reached out to His people through mediators who spoke on His behalf, defining the terms of the relationship through what we call covenants. God initiated many different covenants with His people. Some were conditional and some were unconditional, but they all communicated His desire to maintain His love relationship with His people. The two most significant covenants were the Covenant of Works and the Covenant of Grace. 

The Covenant of Works

Beginning in the garden, God made a conditional covenant with man: if man obeyed God, he would be rewarded with life, and if man disobeyed God, he would face death. Man’s response to God determined the outcome of the covenant. The people of God lived under a covenant of works for centuries, learning again and again that due to our sin nature, inherited from Adam, no one can perfectly obey God and secure salvation for himself. Man could not maintain his relationship with God by his own works. Instead, man needed a covenant of grace.

Looking Forward to the Covenant of Grace

Mankind’s sinfulness merited death according to the covenant of works, however, God in His grace already had another plan in place.

God used many mediators in the form of prophets, priests, and kings after Adam to communicate the terms of both the old and new covenants. Each mediator received new revelations from God and each piece of information would fit together with the other pieces like a beautiful puzzle. These mediators worked on behalf of the people to maintain relationship with God, and sought to help the people remain faithful in covenant with Him. For a while, people lived under the covenant of works but with hope in a new and better covenant to come.

Priest as Mediator

Under the covenant of works, God required that spotless, perfect animals be killed to pay for sin. Through the mediation of Moses as a priest, God explicitly explained to the people the details of His requirements for acceptable sacrifices (Lev. 4). These sacrifices were done by priests on behalf of the people in order to restore the relationship between God and His people that had been broken by sin. Although the sacrificial system was a requirement of the covenant of works, it also served to foreshadow the blood sacrifice that God would have to make in order to fulfill the covenant of grace.

King as Mediator

King David was a (generally) godly king whom God used to set the stage for the covenant of grace. God made a special unconditional covenant with David, which promised that a Messiah would come through his lineage and that this Messiah would also reign over God’s kingdom forever as a perfect King (2 Sam. 7). This entire covenant was based on grace. God would fulfill His part of this covenant no matter what actions Israel made.

Prophet as Mediator

God used a prophet named Isaiah mightily to rebuke God’s people for breaking the covenant of works by the many sins they had committed against God (Isaiah 1-11). God also used Isaiah to prophesy to His people of the coming Messiah. Through Isaiah, God taught His people that the Messiah would be born of a virgin and would suffer on their behalf (Isaiah 7:14; Isaiah 53). These details and many more were given so that God’s people would be able to recognize and worship the Messiah when He appeared. Properly identifying the Messiah would be a key element of being included in the covenant of grace.

The Covenant of Grace

The long-anticipated covenant of grace was going to be drastically different from the covenant of works. In the covenant of works, man was required to perfectly obey God in order to be in relationship with Him. This would not be the case in the covenant of grace. God knew that His people were sinful and incapable of perfect obedience on their own. God himself would make sure that the requirement of perfect obedience was fulfilled. But how would it be fulfilled?

In addition, the requirement and means by which His people could enter this covenant with Him would be faith, not works. This faith would not be their responsibility to manufacture. Faith would be given to God’s chosen people as a gift. But what would be the object of the people’s faith?

The answers were finally found in the long-awaited Messiah—Jesus Christ. He was the final piece of the puzzle.

• Jesus, the second person of the Trinity, came down to earth as a baby, born to a virgin.
• Although He was human, He also maintained His deity.
• Jesus perfectly obeyed the covenant of works that Adam (and we) failed to obey. When He did this, He fulfilled the requirement of the law on our behalf.
• Even though Jesus was sinless, He willingly died a criminal’s death on the cross. Jesus’s perfect, spotless obedience—combined with His infinite existence (because of His deity)—qualified Him to be the ultimate Sacrifice. His death was a sufficient payment for the sins of all of God’s people, ending the necessity for more sacrifices.
• After three days in the grave, God raised Jesus back to life, showing that Jesus indeed had power over sin and death. This victory would fulfill the promise that God had made to Adam and Eve after the fall. Jesus was their offspring who would crush the head of Satan.
• God sent the Holy Spirit to His people to gift them with faith in Christ as the Messiah and to give them new hearts. Now God’s people would be able to really know God and obey His commands.

Because Jesus fulfilled the requirements of the old covenant, He became the Sole Mediator of the new and better covenant (Heb. 8:6; 9:15). We need no other mediator between God and Man; Jesus is enough (1 Tim. 2:5). He is our perfect Prophet, Priest, and King.

Editor's Note: This originally published at Thinking & Theology