Andrew Sullivan says he’s appalled at the resignation of Firefox CEO Brendan Eich, who quit yesterday following a backlash over his appointment due to his previous financial support for anti-equal marriage campaigners.

Mozilla, the company behind the Firefox web browser, announced on Thursday evening that Mr Eich had resigned as chief executive.

Earlier this week Mr Eich vowed to remain in post, saying: “I’m the best person for the job”.

The Mozilla co-founder blasted dating website OKCupid for urging its members to boycott the Firebox web browser over last month’s appointment of Mr Eich as Mozilla CEO.

In a show of support for Mr Eich, author, editor and blogger Andrew Sullivan said “gay activists” had gone too far.

He wrote on The Dish: “The guy who had the gall to express his First Amendment rights and favour Prop 8 in California by donating $1,000 has just been scalped by some gay activists.”

Mr Sullivan continued: “Will he now be forced to walk through the streets in shame? Why not the stocks? The whole episode disgusts me – as it should disgust anyone interested in a tolerant and diverse society. If this is the gay rights movement today – hounding our opponents with a fanaticism more like the religious right than anyone else – then count me out. If we are about intimidating the free speech of others, we are no better than the anti-gay bullies who came before us.”

It was revealed in 2012 that Mr Eich donated $1,000 (£605) in 2008 to the campaign supporting California’s Proposition 8, whilst he was Mozilla’s chief technology officer.

The Prop 8 law banned same-sex marriages in the state and was finally struck down by the US Supreme Court after years of legal battles in June 2013.