As a child growing up in Phoenix, on most Sunday mornings (at least those I wasn’t playing hooky), one would have found me at the big downtown Central United Methodist Church. It wasn’t the nearest Methodist church, but it did have the best choir. Closest to home was a beautiful little church in the style of Southwestern Spanish missions, Bethel United Methodist. It was small and sleepy and losing parishioners at a rate that would lead to the church calling it quits in 2007.

Shockingly, given Arizona’s careless disregard for what little architectural history it has (a decade ago, developers nearly bulldozed one of Frank Lloyd Wright’s last and best structures, the David and Gladys Wright House), the abandoned Bethel building wasn’t torn down. Instead, it was reborn several years ago as a high-end, high-concept Mexican restaurant, Taco Guild.

The joint makes the most of its ecclesiastical past, even if the restaurant is somewhat confused about the building’s denominational roots. For example, instead of a “happy hour,” the bar has a decidedly non-Methodist “confession hour.” That said, given the teetotaling tendencies once dominant in their identity, the very concept of drinking would be appalling to old-school Methodists. Drinking in what had once been a Methodist church would be particularly anathema.

I found myself at the Taco Guild bar the other evening with two margaritas in front of me, one the “house margarita,” the other a drink labeled the “Holy Grail” — not, I should point out, a “Holy Grail margarita” but simply a "Holy Grail" — which raises the question: When does a margarita cease to be a type of margarita and become another drink altogether?

There is a long tradition of specifying what would otherwise be the generic ingredients that make a margarita and giving that drink a specific name. There are three basic ingredients in a margarita: tequila, orange liqueur, and lime (or lemon). There are hundreds of brands of tequila and multiple expressions, such as silver (or unaged) and reposado (minimally aged in oak), of each brand. Not as expansive as the selection of tequilas, there is still a variety of orange liqueurs to be used in balancing the drink’s tart citrus. There are generics such as “triple sec” and famous brands such as Cointreau. There are even multiple choices within a brand: The drink can be made with brandy-based Grand Marnier, for example, or, if one is in the chips, with the pricey Grand Marnier Cuvee du Centenaire, which uses 25-year-old cognac.

Let’s say there are 100 tequila choices (a gross underestimate) and 10 types of orange liqueur. There alone you have a thousand possible combinations for a margarita. If you give each variant its own name, you’re going to get a rather long drink list.

Or, if you edit those thousand drinks down a bit, you’ll end up with something like the “Great Margarita List" at Maria’s in Santa Fe, New Mexico. It features some 70 individually named iterations of the classic cocktail. There’s the “Infinity” (Clase Azul Plata and Cointreau), “El Grandioso” (Exotico Reposado and Grand Marnier), “Silver City” (Herradura Silver and triple sec), and so on, nearly without end.

It may seem silly to give a classic a different name based on ingredient brands, and at Maria’s, the shtick is clearly out of control. But what about the Holy Grail in front of me at the old Bethel?

There is an effort that goes into the mix that makes it both specific and hard to copy. Restaurant co-owner Dominick Scarpinato travels to Jalisco, Mexico, to the La Altena distillery where El Tesoro tequila is made. He selects an individual barrel of aging tequila to be bottled solely for Taco Guild. Combine the bespoke El Tesoro with Cointreau, lime juice, and a little simple syrup to taste, and you get a margarita so good that Taco Guild can call it whatever they want.

Eric Felten is the James Beard Award-winning author of How's Your Drink?