Testifying before Congress about religious liberty last February, William Lori, archbishop of Baltimore, proffered an analogy. The government would not force a kosher deli to serve ham sandwiches, Lori observed; so why force Catholic hospitals to provide their employees with contraception coverage?

I was surprised that a bishop would make this comparison—and certain that Aquinas would have been shocked. Catholics traditionally have seen the prohibition against contraception as a moral norm binding on all human beings, like prohibitions against murder, theft, and lying; by contrast, the laws of kashrut are cultic precepts that bind only Jews. But then I began to wonder whether Lori was on to something. From a sociological perspective, the prohibition against contraception does seem to be morphing from a universally applicable moral norm into a cultic norm that marks and defines Catholic identity—one strict form of it, anyway—within a broader pluralistic culture.

Traditionally, Catholics don’t build religious identity around adherence to absolute negative moral norms, but rather view those norms as the foundation of an acceptable moral identity. Yet many Orthodox Jews (especially those living in pluralistic societies) do build their identity around the laws of kosher, measuring their religious and communal commitment through their recognition of ritual laws of purity and contamination.

Thanks to John Paul II’s “Theology of the Body,” a small but dedicated group of Catholics appears to be structuring their family lives around the prohibition of contraception. In treating that prohibition as the linchpin of a faithful Catholic life, including faithfulness to divinely ordained gender roles, they are transforming the prohibition into a religious identity marker. If their blogs are any indication, Catholics who publicize their commitment to this church teaching tend to see those who don’t follow it as inauthentic Catholics. That is more akin to a cultic judgment than a moral one. Significantly, no one talks about the prohibitions against stealing, lying, or murdering this way. Someone who commits murder would be labeled a sinner or a bad Catholic—not an inauthentic one.

The similarities go further. Conformity to cultic norms generally takes a great deal of thought and vigilance, and Natural Family Planning demands ongoing vigilance in ways analogous to keeping kosher. Just as there are competing rabbinical schools, there exist NFP experts, as well as study groups and manuals, to address technical questions. Not surprisingly, enterprising adherents to both Jewish dietary prohibitions and the Catholic ban on contraception have invented smartphone apps to make conformity easier.

In contrast, I’m not aware of an app for “not killing”—or “not stealing,” for that matter. That’s because most people don’t spend too much time thinking about whether and how to conform to basic moral prohibitions. In fact, the more fundamental the moral prohibition, the less time we ought to think about it. We would worry greatly about someone who said, “I want a promotion. I could kill my boss and take her job... but that would be wrong.” Killing the boss is or should be unthinkable.

A critic might object by noting that some Catholics forgo both birth control and NFP, “leaving room” for God to plan their family. But this approach is also strikingly inconsistent with the way negative moral prohibitions operate in the Catholic tradition. After all, no one says, “I’m leaving room for God to plan my career, so I’m not going to steal my coworker’s ideas.” In the Catholic moral framework, the point of negative moral absolutes is to conform to God’s law, not to leave room for divine providence to operate. Our tradition does not frame the relationship of God’s will and human activity in this mutually exclusive way.

Can’t the norm against contraception be both a universal moral norm and a cultic Catholic one? From a sociological perspective, pulling this off would be tricky. General moral norms are meant to gather all people together into the same moral community, highlighting commonality. (Think, for example, of the Universal Declaration on Human Rights.) Cultic norms, by contrast, emphasize differences among subcommunities, focusing on what sets them apart.

A hundred years from now, no one will remember the political skirmishes around religious liberty during the 2012 presidential campaign. But some future historians of Catholic moral theology might point to Bishop Lori’s testimony as a turning point, marking the moment when the church’s official teachers began to concede that the prohibition against contraception could plausibly be defended no longer as a matter of a universal moral law, but only as a cultic precept binding on Catholics. Four decades after Humanae vitae, that prohibition looks increasingly like a form of Catholic kashrut.

For more coverage of the contraception mandate, click here.