“He can still keep his personal beliefs, but …”

It seems there’s always a “but” when it comes to acting on certain beliefs these days.

You can operate a closely held family business according to your faith, but … you better not object to any government health mandates.

You can have strong political opinions and a lot of money, but … don’t be getting the idea you can spend much money to promote those who share your political opinions.

And in the recent case from which this column’s opening words came: You can donate to a political cause you believe in, but … don’t expect to keep your job.

In late March, Brendan Eich was named the new chief executive of Mozilla, maker of the Firefox web browser and a company he co-founded. Within days, a small app developer said it would stop offering its products via Firefox. Days later, an online dating service began advising customers not to access its site with Firefox.

Days after that, Eich was the ex-CEO of Mozilla.

Why did the other businesses object to Eich’s hiring? Because six years ago, he donated $1,000 to the Proposition 8 campaign in California, which sought to limit marriage in that state to unions of one man and one woman.

The ballot measure was approved — after a campaign that cost the competing sides a combined $83.1 million — and then thrown out by courts as unconstitutional, all before Eich’s hiring. No matter. Mozilla relented to external and internal pressure and deposed its new CEO after less than two weeks on the job.

Twisting a line used by social conservatives, some gay-marriage advocates have suggested this was just “the market” at work, rendering cold economic justice.

Really? Eich gave 1 percent of 1 percent of the money spent on a referendum campaign. His hiring was challenged by an app maker (Rarebit) whose products draw tens of thousands of users in an industry that has seen tens of billions of downloads, and a website (OK Cupid) ranked as the 422nd most popular in the world.

In the week before Eich left the company, Mozilla’s publicly self-reported complaints averaged about 1,500 a day, many of them condemning his appointment. In the week after, they averaged about 7,000 a day, most of them condemning his ouster. But he’s still out of a job.

That’s “the market” at work?

This is more than a heckler’s veto. It’s high-tech vigilantism, in which a self-commissioned thought posse enforces its speech code in a way our own government is rightly barred from trying.

Once it was over, the vigilantes feigned remorse for the career-blood on their hands. “I want to say how absolutely sad (sic) to hear Brendan Eich stepped down,” wrote one of Rarebit’s co-founders (it’s unclear which one) on the company’s blog. “He can still keep his personal beliefs, but” he should have apologized.

This, 10 days after writing, "We will continue our boycott until Brendan Eich is completely removed from any day to day activities at Mozilla" (emphasis added). And six days after writing a post titled "Five Reasons Eich Should Step Down."

Perhaps the thought posse didn’t think things over as thoroughly as it had let on.

And perhaps we should think twice before accepting this sort of advocacy — sure to cross over to other purposes, by other users, if it proves both successful and acceptable — as the new norm.