What Does it Mean to Say Jesus has Fulfilled the Old Covenant?

A reader writes:

I am having difficulties understanding when to apply teachings from the Old Testament and when those laws have been fulfilled completely and can be disregarded.  For example, the Church bases her teachings on contraception at least partially on the sin of Onan yet she doesn’t teach the other half of the story that involves sleeping with your brother’s wife shall he die (Thank You).

I understand that some teachings were given to the Israelites through Moses due to the certain circumstances that they were in.  But doesn’t the church use some of these teachings at times and at other times disregards them as “fulfilled”?

I’ve dealt with people who challenge Christianity by challenging these early teachings that seem barbaric to them.  I just don’t know when to take Old Testament teachings and apply them in life and when to say that these laws have been fulfilled by Jesus.

I think it’s a mistake to speak of “disregarding” parts of the Old Testament.  It’s true that the ceremonial laws of the Old Covenant are not binding on Christians.  But those laws were there for a reason and so even though we do not have to, for instance, practice circumcision or slaughter Passover lambs, we do need to “regard” those laws in the sense that we have to ask why God gave them in the first place and what it is, in the New Covenant, that they foreshadow.  So, for instance, circumcision is a prefiguration of the “circumcision of the heart” we receive through the grace of baptism and the Passover Lamb is the divinely chosen image of Jesus, the Lamb of God.  So far from disregarding such Old Testament images, we should seek to understand and plumb their meaning as deeply as possible, in order to understand who Jesus is and what he has done for us.  That is why he himself says that he has not come to abolish, but to fulfill the law and the prophets (Matthew 5:17).

That said, a good rule of thumb when looking at the Old Testament, particularly with regard to morality, is to pay attention to the natural law, but to also be aware that the Old Testament is, by its nature, incomplete and awaiting fulfillment in the New.  So, for instance, the New Testament has no particular words of rebuttal to “You shall not murder” or “You shall not commit adultery”.  At the same time, the New Testament will raise these commandments in various ways, by alerting us to the core issue, which is sin in the heart.  So Jesus warns that if we hate our brother or sister or lust after our them, we have already committed murder and adultery in the heart.  So far from teaching us to disregard the Old Law, the New Testament instead heightens our understanding of what it means and points us to “the heart of the law”.

In the case of Onan, you are right that the common Catholic reliance on this passage as a proof text against contraception or masturbation is a weak one and wrong-headed.  The point of the story is that Onan dishonored the natural law by failing to provide an heir for his brother and his widow (recall that children were the sole “social safety net” that widows had, so the main sin in view in the text of Genesis is Onan’s betrayal of his family by refusing to give his brother’s wife children after his brother had died).  However, those who think that dismissing this particular proof text as an arguement against contraception means that the entire tradition of Catholic sexual morality is therefore rendered null and void simply have not grappled seriously with that tradition.  For the real basis of Catholic teaching here is not this badly applied proof text, but with the nature of human sexuality.  In that tradition, God is the author of nature and our task is to cooperate with, rather than thwart it.  For more details on this, see my “Cooperating with the Creator”.  The quick summary is that that sex has two purposes revealed to us in the Creation account: union with the beloved (“the two shall be one flesh”) and fruitfulness (“be fruitful and multiply”).  It is legitimate to cooperate with nature by, for instance, choosing to have sexual relations during a woman’s infertile period.  But what artificial contraception does is attempt to stripmine pleasure from the sexual act while regarding both union with the other person and the life of the child as entirely secondary to Me ad My Pleasure.

This means that the Catholic insistence on cooperation with, rather than defiance of, nature is not a matter of ritual or ceremonial defilement (such as eating pork would be for a Jew or touching a dog would be for a Muslim) but is rather (like all matters of the natural law) about things which pertain to the good of human beings as human beings, like the prohibitions against adultery, theft, or murder.

Of course, all this requires a fair amount of discernment, but at the same time, it’s not impossible to work out.  A good rule of thumb is that if something is part of the ceremonial or ritual law of Israel (diet, liturgical observances such as Passover or Hanukkah, clothing, etc.) Christians are not bound by it and (should they seek to be justified in the sight of God by such observances rather than by Christ) keeping these ritual requirements of the Old Law can even be harmful (that’s what the letter to the Galatians is concerned about).  On the other hand, the moral teachings of Israel remain binding, as long as we recognize where the New Testament has perfected and raised them.  So, for instance, under the Old Covenant you loved your neighbor and hated your enemy.  Under the New, we are to love even our enemies (not a popular teaching).  Likewise, under the Old Covenant, divorce was permissible.  Under the New, Jesus tells us this was only permitted due to the hardness of our hearts and forbids divorce.

One of the functions of the Magisterium, teaching us through such instruments as the Catechism, is precisely to help us navigate this.  Start with the big and simple commands to love God and neighbor and work from there.  Paul tells us that the main issues are love, joy, and peace in the Holy Spirit, not what we eat.  Jesus, likewise, declares all foods clean.  And this goes for the rest of the Jewish ceremonial laws.  At the same time, of course, Jesus expects us to fast (Matthew 6:16-18) and the Church focuses on fasting in particular during Lent.  But that’s not because food is unclean, but because fasting is a way of practicing self-denial and “taking up our cross” as Jesus says to do.  So this goes back, once again, to our keeping the moral law of love for God and neighbor.

Hope this helps!