Q: Why don’t we follow all of the laws of the Bible? Like, what about Old Testament dietary laws, or going to synagogue on Saturday, or laws about stoning someone if they commit adultery?
A: This is a very important question. I have encountered quite a few people who will try to cite the rules of the Old Testament that we no longer follow (like those you mention in your question) as “proof” that certain moral commands of the Old Testament can be disregarded. I have even met people who claim that this seeming discrepancy means that there is an “Old Testament God” and a “New Testament God”. Both of these claims are false and Catholics need to be able to articulate how these arguments are nothing but empty errors.
To begin, we need to grasp the necessity of the Old Testament. The entire Bible is “Christocentric”. This means that all of it somehow points to Jesus Christ and is somehow fulfilled in Jesus Christ.
This is one of the reasons why we need to be rooted deeply in the Old Testament. First, because it is the Word of God given to man. This means that it has a depth and a treasure to it that cannot be measured or plumbed or understood in human terms. Second, if we are going to understand Jesus, we need to understand His world and worldview. The Old Testament captures Jesus’ roots and without it, we have truly no hope of understanding Him in the slightest. At worst, we will “get Jesus wrong” and fashion Him into a creation of our own minds and worldviews (Jesus ends up looking like a 21st century American, or a 20th century civil-rights leader, or a Central American Freedom Fighter rather than a 1st century Jew living in Palestine). Jesus’ words and teachings and miracles have a context; they rise out of the original covenants God made with His People. Third, we begin to see the way in which the Old Covenant is completely fulfilled in Jesus. Jesus is the One in whom Justice and Mercy meet. Not as a contradiction, but as the only solution to the otherwise irreconcilable dilemma of condemnation versus forgiveness. Like harmony and melody are in one song, the God of the New and Old Testaments is ONE.
Once we begin to understand the Old Testament more fully, we begin to see that there are three different “groups” of laws: moral laws, laws that surrounded Temple worship, and “Kingdom laws”. While a novice might pick up the Bible and not notice a distinction, one who has taken the time to study and pray through the Bible will notice that these three types of laws are very different (and somewhat obvious).
Moral laws are laws governing behavior that are true at all times in all places for all people. The Ten Commandments are the prime example of these. They don’t pass away. They are neither culturally nor historically conditioned. They are not based on situation but on the very nature of the human person and who God has revealed Himself to be. These are absolutely true and good for all people everywhere.
Laws surrounding Temple worship are another category altogether. The Temple was the center of worship for a Jew. We sometimes think that the synagogue is the center, but this is only a relatively recent development since around 70 AD. Until the final destruction of the Temple in Jerusalem by the Roman Empire toward the end of the first century, the Temple was the heart of Jewish life. While synagogues were places of study and prayer, it was in the Temple that the fullness of Jewish worship occurred. It is no surprise then to find quite a few rules about how Jews were to worship in the Temple. There are rules for ritual purity as well as how and when to enter the Temple (and what to do once a priest was inside!).
We need to remember that the Bible was written in a real historical context.
All that being said, the Temple no longer exists. Does it make any sense to retain the laws regulating Temple worship? Not at all. These laws have not so much “passed away” as “found their fulfillment” in the worship of Jesus in the Catholic Mass. But we have no obligation to follow them because there is no Temple, get it?
The same is true for the third grouping of rules: Kingdom laws. We need to remember that the Bible was written in a real historical context. Much of it was written in the context of the emerging People of Israel; a tribe that eventually became a Kingdom. These “kingdom laws” existed for (at least) two reasons. First, so that the people of Israel would have laws for order and living as a nation. These laws may be just, but in some ways arbitrary (like the speed limit; there is no speed limit applicable at all times in all places). Second, to ensure that these people would live in a way that is distinct. It would help them retain their unique relationship with God while living in the midst of people who were outside the covenant. The need for this should be obvious to us. It doesn’t take a lot of brain cells to recognize how difficult it is to live one’s Faith when surrounded by people with whom you have no shared Faith. This is one of the reasons why St. Paul wrote that Christians ought not to marry someone who is not a believer. Not because non-Christians (or more specifically: non-Catholics) are bad, but because it is really hard to share your life with someone and avoid being shaped by their beliefs. For the same reason, Jews were called to live apart from Gentiles (non-Jews). Not because Gentiles were intrinsically evil, but because cultures and beliefs would mix and they would “get God wrong”.
Therefore, there are certain rules about what to wear and what to eat that demand that the Jew live a life separate from the Gentiles around him. These restrictions are lifted for two reasons: the Kingdom of Israel no longer exists and Christians are called to be distinct in a new way; as spelled out in the New Testament and by the Catholic Church. These Kingdom rules have served their purpose, they are no longer necessary.
There are certain rules that cease to apply because there is no context for them (no Temple or Kingdom). The moral rules still apply because the context (living as a human) has not changed. Get it?