A number of years ago, I went to my 10th high-school reunion, in the backyard of the one classmate whose parents had a pool. Lots of my classmates were there. Almost all were married, and many already had kids. This was not as unusual as it might seem, since I went to a yeshiva day school, and nearly everyone remained Orthodox. I brought my girlfriend. At the end, we all crowded into a big group photo, shot by the school photographer, who had taken our pictures from first grade through graduation. When the alumni newsletter came around a few months later, I happened to notice the photo. I looked, then looked again. My girlfriend and I were nowhere to be found.

I didn’t want to seem paranoid, especially in front of my girlfriend, to whom I was by that time engaged. So I called my oldest school friend, who appeared in the photo, and asked for her explanation. “You’re kidding, right?” she said. My fiancée was Korean-American. Her presence implied the prospect of something that from the standpoint of Orthodox Jewish law could not be recognized: marriage to someone who was not Jewish. That hint was reason enough to keep us out.

Not long after, I bumped into the photographer, in synagogue, on Yom Kippur. When I walked over to him, his pained expression told me what I already knew. “It wasn’t me,” he said. I believed him.

Since then I have occasionally been in contact with the school’s alumni director, who has known me since I was a child. I say “in contact,” but that implies mutuality where none exists. What I really mean is that in the nine years since the reunion I have sent him several updates about my life, for inclusion in the “Mazal Tov” section of the newsletter. I sent him news of my marriage. When our son was born, I asked him to report that happy event. The most recent news was the birth of our daughter this winter. Nothing doing. None of my reports made it into print.

It would be more dramatic if I had been excommunicated like Baruch Spinoza, in a ceremony complete with black candles and a ban on all social contact, a rite whose solemnity reflected the seriousness of its consequences. But in the modern world, the formal communal ban is an anachronism. Many of my closest relationships are still with people who remain in the Orthodox fold. As best I know, no one, not even the rabbis at my old school who disapprove of my most important life decisions, would go so far as to refuse to shake my hand. What remains of the old technique of excommunication is simply nonrecognition in the school’s formal publications, where my classmates’ growing families and considerable accomplishments are joyfully celebrated.

The yeshiva where I studied considers itself modern Orthodox, not ultra-Orthodox. We followed a rigorous secular curriculum alongside traditional Talmud and Bible study. Our advanced Talmud and Hebrew classes were interspersed with advanced-placement courses in French literature and European political history, all skillfully coordinated to prime us for the Ivy League. To try to be at once a Lithuanian yeshiva and a New England prep school: that was the unspoken motto of the Maimonides School of Brookline, Mass., where I studied for 12 years.

That aspiration is not without its difficulties. My own personal lesson in nonrecognition is just one small symptom of the challenge of reconciling the vastly disparate values of tradition and modernity — of Slobodka and St. Paul’s. In premodern Europe, where the state gave the Jewish community the power to enforce its own rules of membership through coercive force, excommunication literally divested its victim of his legal personality, of his rights and standing in the community. The modern liberal state, though, neither polices nor delegates the power to police religious membership; that is now a social matter, not a legal one. Today a religious community that seeks to preserve its traditional structure must maintain its boundaries using whatever independent means it can muster — right down to the selective editing of alumni newsletters.

Despite my intimate understanding of the mind-set that requires such careful attention to who is in and who is out, I am still somehow taken by surprise each time I am confronted with my old school’s inability to treat me like any other graduate. I have tried in my own imperfect way to live up to values that the school taught me, expressing my respect and love for the wisdom of the tradition while trying to reconcile Jewish faith with scholarship and engagement in the public sphere. As a result, I have not felt myself to have rejected my upbringing, even when some others imagine me to have done so by virtue of my marriage.