The concept of the Old Covenant, primarily established through the Mosaic Law, is foundational to understanding the narrative of the Bible and the development of the New Covenant through Jesus Christ. The Old Covenant, given to the Israelites at Mount Sinai, is characterized by a series of laws, rituals, and sacrifices designed to set Israel apart as God's chosen people. The New Covenant, as revealed in the New Testament, brings a transformative shift in how God's relationship with humanity is understood and experienced.

1. Nature of the Covenants

The Old Covenant was conditional, based on the adherence to the Law given through Moses. It included moral, ceremonial, and civil laws that governed the life of Israel. In contrast, the New Covenant is unconditional, established through the sacrificial death and resurrection of Jesus Christ. It is based on grace and faith rather than adherence to a set of laws. Hebrews 8:6 states, "But now Jesus has received a more excellent ministry, just as the covenant He mediates is better and is founded on better promises."

2. Mediators of the Covenants

Moses served as the mediator of the Old Covenant, acting as the intermediary between God and the Israelites. In the New Covenant, Jesus Christ is the sole mediator. 1 Timothy 2:5 affirms, "For there is one God and one mediator between God and men, the man Christ Jesus." This highlights the direct access believers have to God through Christ, contrasting with the priestly system of the Old Covenant.

3. Sacrificial System

The Old Covenant required continual animal sacrifices to atone for sin, which were a foreshadowing of the ultimate sacrifice to come. The New Covenant, however, is marked by the once-for-all sacrifice of Jesus. Hebrews 10:10 declares, "And by that will, we have been sanctified through the sacrifice of the body of Jesus Christ once for all." This signifies the completion and fulfillment of the sacrificial system.

4. Law and Grace

Under the Old Covenant, the Law was central, serving as a tutor to lead people to Christ (Galatians 3:24). The New Covenant emphasizes grace, with salvation being a gift from God, not earned by works. Ephesians 2:8-9 states, "For it is by grace you have been saved through faith, and this not from yourselves; it is the gift of God, not by works, so that no one can boast."

5. Internal vs. External

The Old Covenant focused on external adherence to laws and rituals. The New Covenant, however, emphasizes an internal transformation. Jeremiah 31:33 prophesies this change: "But this is the covenant I will make with the house of Israel after those days, declares the LORD. I will put My law in their minds and inscribe it on their hearts. And I will be their God, and they will be My people." This internalization of God's law signifies a deeper, more personal relationship with God.

6. Scope and Inclusivity

The Old Covenant was primarily with the nation of Israel, setting them apart from other nations. The New Covenant, however, is inclusive, extending to all people, Jews and Gentiles alike. Galatians 3:28 emphasizes this inclusivity: "There is neither Jew nor Greek, slave nor free, male nor female, for you are all one in Christ Jesus."

7. Promise of Eternal Life

While the Old Covenant contained promises of land and prosperity, the New Covenant offers the promise of eternal life. John 3:16 encapsulates this promise: "For God so loved the world that He gave His one and only Son, that everyone who believes in Him shall not perish but have eternal life." This promise of eternal life is central to the hope offered in the New Covenant.

In summary, the contrast between the Old and New Covenants highlights a shift from law to grace, from external adherence to internal transformation, and from a focus on a specific nation to an inclusive promise for all humanity. The New Covenant, mediated by Jesus Christ, fulfills and transcends the Old, offering a new way to relate to God through faith and grace.