For many fans, the replica NFL jerseys they've been purchasing in ever-growing numbers since the 1990s are religious vestments.
Donned with faith on Sundays, imbued with spiritual significance, their unique color and design reveal their wearers' sectarian leanings, their communion with fellow believers. Alter these sacred garments and you risk being tarred as a heretic.
If Eagles supporters needed a reason to dislike Jeffrey Lurie - and this being Philadelphia, antipathy toward ownership is as natural a state as low expectations - he provided them with a solid one not long after purchasing the team in 1994.
Lurie, for reasons that have always been murkier than his adopted city's drinking water, changed the Eagles' dominant color from the garish kelly green it had worn since the late 1940s to a darker, more subtle midnight green.
While it was a fashion decision Vera Wang likely would have endorsed, many Philadelphians never embraced it.
So when, this summer, a team official hinted at another green revolution - a Kelly-era return to kelly - the news was roundly applauded.
"Uniforms get into the hearts and minds of fans," said Peter Capolino, a founder of Mitchell & Ness Nostalgia Co. "The kelly green ones were closely identified with the Eagles. Steve Van Buren and Chuck Bednarik wore them, and the team won championships in them. They were a tradition that fathers passed along to their sons."
The midnight-green Eagles, of course, have won no championships. The emotional connection to them, as a result, is not nearly as deep. And while that more-subdued color might have fulfilled some post-1960s urge for understatement, the team's uniforms are beginning to look frumpy in an era when college fashions, in particular, are going kaleidoscopic.
Should NFL marketers approve the change, what exactly will this latest generation of kelly-green jerseys look like? Will they be replicas of the ones Van Buren or Chuck Bednarik wore or those that Randall Cunningham and Reggie White played in?
Whatever, since there is no uniform Eagles uniform, it won't be an easy decision.
Even during the long reign of kelly green, there were numerous incarnations. Some had white-striped sleeves. Some had large numbers front and rear. Others mixed large and small. Some incorporated the team's logo.
And will they include any of the black that Lurie also added to the team's palette? Or be tweaked with some new fashion twist to make them distinctively 21st century?
The Eagles' first uniforms weren't green at all, but rather baby blue and yellow, an homage to Philadelphia's city colors and the flag of Sweden, whose emigrants were this area's first European settlers.
That color scheme made a brief throwback comeback in 2007. Even though the Eagles won that day, thrashing the Detroit Lions, 56-21, fans chided the uniforms as "kitschy" and "just plain ugly," and they were never resurrected.
"Throwbacks?" then-MSNBC commentator Keith Olbermann remarked, "Try throw-ups."
We are living in a golden age of uniforms. Originally intended merely to distinguish one team from another, they've morphed into extremely creative, extremely lucrative, and extremely desirable merchandise, items no true believer can live without.
At any Eagles game, so many spectators are in jerseys that Lincoln Financial Field resembles a summer hillside, its grandstands speckled with various shades of green.
Capolino and his Philadelphia-based company are as responsible as anyone for the boom, especially when it comes to vintage jerseys. Mitchell & Ness began making the Eagles uniforms in the 1930s and virtually created the jersey-nostalgia boom six decades later.
There was a time when uniforms were just uniforms, and, though a limited number had been available in sporting-goods stores since the 1970s, few fans were interested in wearing them.
But in 1991, the NFL, sniffing revenue potential, started encouraging experimentation and kicked its merchandising machine into high gear. Logos were put on the sleeves, NFL shields were added to the collars, and teams began developing alternative versions.
Then in the late 1990s came the throwbacks, a craze accelerated by all the rap and hip-hop artists who had a penchant for wearing them in videos and at awards shows.
It all succeeded so well that for the first time last season, the sale of official NFL merchandise - with jerseys making up the overwhelming share - topped $1 billion.
So deeply has this uniform trend taken root in sports, and so creative and constant are its iterations, that some now see it all as art.
On Sept. 10, for example, at the Fleisher Memorial Art Sanctuary on Catherine Street in South Philadelphia, Capolino will display and discuss 40 different uniforms that the Eagles wore between 1933 and 1963.
"In baseball, there's probably more variety of graphics and design," he said. "In football, it's mostly numbers, stripes, and colors. But you look at things like the fabrication and the lettering and you realize it really is a kind of art."
It might be.
But when it comes to the uniform craze, the artistic designers still have to take a backseat to the most creative geniuses in sports history - the NFL's merchandisers.