A troubled 30-something and a man of the cloth might seem unlikely influencers, but these are just two examples of “the Fleabag effect.” When the new season aired in Britain, it became a rare phenomenon in these days of fragmented TV viewing. The final episode was watched on the BBC by 2.5 million, a high figure for an alternative comedy — and nearly a quarter of all 16- to 34-year-olds who were watching TV at the time were tuned in.

[Read our review of Season 2 of “Fleabag.”]

It also became one of the most talked-about shows in Britain in years, thanks largely to the odd-couple chemistry between the attractive priest and the nihilistic heroine. As viewers debated the ins and outs of their relationship on social media, the show became daily fodder for newspaper columnists. “Is Fleabag good for Catholicism?” asked one. “Fleabag is a work of undeniable genius. But it is for posh girls,” declared another.

Just as the fervor was dying down, on May 2, Waller-Bridge announced a revival of her original “Fleabag” stage show in the West End of London, after a run at the SoHo Playhouse in New York last month. She tweeted a single word — “London!” — and a winky-face emoji, and all 30 dates sold out in an hour. Some fans waited online for three hours to get tickets for the 65-minute monologue, which cost up to the equivalent of about $198. (Some tickets on a resale website were selling for around $775.)

And yet, Waller-Bridge initially didn’t want to write a second season. The first was a sleeper hit which grew out of a one-woman show she performed at the Edinburgh Fringe in 2013. In a recent telephone interview, Waller-Bridge said that the BBC had eventually convinced her and that she had decided she “wanted to write about something bigger, something outside of her own psyche.”

She turned to God. Waller-Bridge said she had been jotting down ideas in a draft email, and when she read it back, she found mainly jokes about religion. (In the first episode, the priest reveals that his brother is a pedophile. He rolls his eyes: “I’m aware of the irony of that.”) A further catalyst was a conversation she overheard between two young women dressed “in really sexy clothes,” debating which part of the Old Testament spoke to them the most. “And something clicked,” said Waller-Bridge. “Modern life and religion felt like the perfect imperfect companions.”