One antonym of monogamy is infidelity. A spouse who is well and truly monogamous is said to be “faithful”; one who steps out, who cheats, is “unfaithful.”

These linguistic choices, with their implicit religiosity, elide and obfuscate as much as they describe and reveal. And much of what they describe and reveal is unintentional.

When we mean to describe the phenomenon of one spouse’s “cheating” on another, we resort to religious language, the language of faith. The sin in infidelity isn’t the sin of the act (adultery). No, it’s the sin of the underlying mental state – faithlessness – that is presumed (proven) to exist by virtue of the act.

But what if one doesn’t believe, but doesn’t act on one’s unbelief? Or worse, if one believes, but acts nonetheless?

Surely many physically monogamous marriages lack faith, and likely, many non-monogamous marriages possess it.

But as the language makes clear, non-monogamy is heresy, faithlessness, atheism, idolatry.

What could possibly be worse?

* Hat tip to Adam Phillips, whose Monogamy is a brilliant, eminently accessible disquisition on the subject. This post is an elaboration of his thoughts on this particular subject. I expect to write more about what he writes in coming days.