Some have called "iconic" while others have dismissed it as "slacktivism."
One thing is for certain: it's ubiquitous.
The image is a red version of the Human Rights Campaign's logo, usually blue with yellow equals sign, which the LGBT activist group shared on Facebook Monday.
"Who's wearing red tomorrow? Show your support for marriage equality -- make your profile image red for tomorrow!" the caption reads.
Almost immediately, the image began to spread across the social network, with the original post shared more than 70,000 times and newsfeeds full of progressive Facebookers showing their support for the repeal of California's Proposition 8 and the Federal Defense of Marriage Act.
(Another version from Tuesday was shared another 70,000 times, and a third, Wednesday, another 7,000. And plenty of parody versions have popped up as well, although most seem to share the original's sentiment.)
The campaign began to pick up steam particularly when actor and Facebook celebrity George Takei made the image his profile picture, but the reaction hasn't been all positive.
Over at Vice, Brian Moylan compared it to wearing green on St. Patrick's Day. In an article titled "The red marriage equality sign on your Facebook profile is completely useless," Moylan accuses the campaign of being an empty gesture.
"Sorry to break it to everyone, but changing your little avatar isn't doing anything to change that," he writes. "Yes, the show of support is heartwarming."
It's nice to see so many people who want their gay friends to be spoiled brides just like all their straight friends, but you're not doing anything. This is just another form of passive activism that isn't advancing the cause. Do you know what would be helpful? Actually picking up a sign, heading down to the Supreme Court, and joining the throngs of protesters.""
And at Policy Mic, Tom Mandel writes that the Red Equal Sign campaign is dumb and "one of the laziest things you can do to support marriage equality."
But gay mag the Advocate called the movement "inspiring," listing a slew of public officials, including several governors, whose profiles went red.
And perhaps the reason the campaign was a success was because social media is a reflection of a significant chunk of the population -- particularly younger people.
While social media sentiment does not necessarily reflect public opinion, polls show gay marriage is gaining significant traction. A CBS poll Tuesday shows a majority of Americans (53 percent) support same-sex marriage -- but among Americans under the age of 30, that number rises to 73 percent.