Watching waves of American visitors visit my synagogue in Jerusalem, I worry about the growing goofiness of even the most serious American Jews. My sons and I have seen leading rabbis wearing Red Sox insignias, reputable businessmen sporting Harley-Davidson logos, kids shamelessly walking around with their faces emblazoned on their bar mitzva kippot, along with the usual Batmans, Supermans and Bart Simpsons. Some of the tallitot young men sport are all New York Yankees emblems or even New York Red Bulls. It’s one arts and crafts project misfire after another.I understand trying to make Judaism fun for little kids by decorating a kippa with a favorite character. I can even understand a religious teenager who wears the kippa full time mixing it up during the week with a favorite sports team’s symbol. But is nothing sacred? It’s bad enough that American corporate capitalism has got us all paying top dollar for the privilege of publicizing products, but ritual objects shouldn’t promote popular culture and commercial ventures. And what’s next? Pictures of a scantily clad Taylor Swift emblazoned on a shofar because she’s musical too? Or maybe synagogues can mimic sports arenas and fund-raise by having Temple Beth Fedex near the Washington Redskins’ Fedex Field, or Ohev MetLife right near the New York Giants’ MetLife Stadium.My daughter once heard a yeshiva kid politely refuse someone offering to crotchet his college logo on a kippa by saying “I only rep Hashem.” He had a point. Hiddur Mitzva, beautifying ritual objects and commandments to glorify God, comes from Exodus 15:2. Amid Moses’s song of salvation after fleeing Egypt, the Jewish people wanted to exalt God. Today’s crass commercialism demeans rather than uplifts.This absurd co-branding reflects a pathological need to make Judaism accessible, digestible, hipper than we believe it actually is. If we believed in it as a serious “product” we wouldn’t prop it up with such idiocy. This injection of popular culture into the sacred is a form of avoda zara, of idol worship. It reflects just how addicted American Jews are to American commercialism and popular culture and how much more comfortable we are speaking the language of materialism rather than Judaism.Judaism should be counter-cultural, resisting popular trends. Instead, Judaism is marketed with props from the very culture it should be critiquing, challenging, rejecting. It’s hard to engage people in serious reflections about a mass addiction to the silliness and superficiality of American popular culture when you’ve Kermit the Frog or Mickey Mouse perched on your head. And, in an election season that is increasingly ugly, partisans should resist parading their Hillary or Trump endorsements while attending synagogue – kippot were intended to show humility, not double as billboards.This Disneyfication of Jewish ritual garments is just one manifestation of a juvenile Judaism that frames Judaism through kids’ experiences and tries boosting our ancient civilization with contemporary shticks. Rather than confronting our heritage as a profound, complex, multi-dimensional phenomenon to stretch us and enrich us, we make it cute and E-Z. In too many liberal synagogues the rabbis talk down to congregants, forgetting that this generation of American Jews is hyper-educated – in secular pursuits, with stacks of PhDs, MDs, MSWs and MBAs. This generation is also Jewishly ignorant – but that requires a sophisticated approach aiming high without presuming too much knowledge. (Orthodox rabbis have an opposite tic, sometimes speaking in a code only insiders understand).This popularization of Jewish ritual objects is the bastard offspring of the 1970s move toward relevance. In havurot, in camps, in bar and bat mitzva classes, Jews started making or decorating Jewish things because Judaism seemed so distant, stiff, foreign. We have now gone overboard. I challenge my rabbinic and educator friends: before running your next bar/bat mitzva art class, where kids express themselves in something Jewish, ask them “what’s appropriate to include and what’s not?” Have them define some boundaries – or admit they believe anything goes.If too much Israeli Judaism and Orthodox Judaism is so rigid as to risk suffocation, too much American liberal Judaism is so open as to risk emptiness. Most Orthodox prayer books lists the laws of what to do if you err during prayer; these “dos” if you did a “don’t” or didn’t do a “do” demonstrate a strong sense of right and wrong. Large parts of American Jewish culture fear this language of Thou Shalts and Shalt Nots is a turnoff in today’s Republic of Nothing. The result often is a lumpy, formless, I’m OK you’re OK, meaningless Jew-ishness.Just as rules enhance games like football and baseball – and music can only be played after a certain minimum of mastery is acquired, Judaism has survived thanks to Jewish rigor, thanks to Jewish law. A Judaism with no imperatives, no commandments, no seriousness, is a Judaism no more lasting than the latest trend, and no more meaningful than the silly symbols invading our sacred spaces.This New Year, let’s learn the power of limits, of discipline, of boundaries. Let’s enhance our objects and practices, not debase them. Let’s make Judaism a sanctuary from commercialism and pop idiocy rather than an extension of it. And let’s see how much more satisfying it is to engage with an authentic Judaism that challenges rather than a faddish Judaism that only entertains.The author, professor of history at McGill University, is the author of The Age of Clinton: America in the 1990s, published by St. Martin’s Press. His next book will update Arthur Hertzberg’s The Zionist Idea. Follow on Twitter @GilTroy.