Why do we believe in some parts (but not all parts) of the Old Testament?

Christians believe that the Old Testament Law given to Moses (which fancy theologians call the “Mosaic Covenant”) was given to and binding only to the ethnic nation of Israel.

A “covenant” means that God gives certain promises to Israel and Israel commits itself to live under God’s laws. These laws can be categorized into rules of holiness (to separate them from the nations around them), civic rules (to create order in society), moral rules (which display God’s nature), and ceremonial rules (to always cause Israel to remember God and their special relationship with him).

These laws, traditionally numbered 613, were in effect for Israel until the coming of Israel’s prophesied King. At this point the Messiah (“Anointed One”) will establish a new and lasting covenant with God’s people which would now also include both believing Jews and Gentiles. This future covenant was prophesied throughout the Hebrew Scriptures.

At Jesus’ arrival, life, death and resurrection, the Old Covenant had been fulfilled. Paul, the letter to the Hebrews, and Jesus’ own words make it clear that Jesus is the fulfilment of the Law and is now the greater Law who demands our faith and obedience. While before, the mark of being among God’s people was through outward expressions (Sabbath worship, circumcision, food laws, etc.), now the mark of being God’s people is through faith and expressions of faith like good works, baptism, and communion.

Is the Law useless?

Now this does not mean that the Law is no longer binding or helpful. First, the Law provides us the narrative framework through which to see Jesus’ life, death and resurrection. The promises, prophecies and stories contained within the Jewish scriptures is the frame through which we must understand Jesus or else we would not understand him at all.

Second, Jesus’ teachings were not revolutionary if you would just immerse yourself in the Old Testament, especially in Deuteronomy and the prophets. Jesus re-affirmed many of the provisions of the Old Testament moral law as being in harmony with New Covenant. Not only did he re-affirm them, he placed the focus deeper into our human nature. For example, Jesus reminds us that not only the act of adultery is a sin against God but also the inward lust that fuels adultery is sin.

And we can learn much from commands of the old Law that were rules of holiness to remind us to be holy today, too. The civic rules remind us that we have a responsibility to build a just society. The ceremonial rules remind us to raise our gaze upward to God and to seek his glory above all.

All of the Law is useful and good. All of the Law is applicable, but not in the same way.