For four days, Daniel Saynt didn’t answer his mother’s constant phone calls.

“I just couldn’t face her,” Saynt recalled. “I had this pit in my stomach. I knew she had found out.”

When he finally answered, his mom could barely speak between sobs. “I’ll never show this to your ­father!” she said.

The shocked mother, a practicing Jehovah’s Witness, was looking at a Jan. 3, 2018, online article about her 35-year-old son — and how he runs one of New York City’s most exclusive millennials-only sex clubs, NSFW (New Society for Wellness).

“She was angry, hurt and worried they’d have to excommunicate me,” The Bronx native told The Post. He had hidden his secrets — about his bisexuality and his free-love lifestyle — from his religious family for years, but was relieved to now be exposed. “I felt like it was time to come forward, and I didn’t want anything to stop me,” he said.

Saynt started his elite sex group, which gathers weekly at a residential three-unit apartment building in Williamsburg, in 2015.

NSFW now has 700 members — all meeting Saynt’s criteria of attractive, successful, avid social-media users — with an average age of 28. There are 300 more people on the waiting list, and more than 9,000 other applicants who didn’t make the cut. The membership fee is a one-time payment of $96, while each sex party carries an extra cost ranging from $30 to $150.

Models, entrepreneurs, singers, actors, media professionals, stylists and A-to-B list celebrities make up the clientele.

“It’s like the Soho House of sex,” said Saynt, referring to the swanky members-only social club.

And it’s a long way from his religious past.

Born Daniel Santiago at Albert Einstein Hospital in the Bronx, Saynt grew up poor and was raised by Puerto Rican parents devoted to their religion. He attended church every Sunday, woke up at 6 a.m. each morning to spread the gospel door-to-door before school and spent 10 hours a week at Bible study. As per the tenets of his religion, he did not celebrate birthdays or holidays, including Christmas.

“It’s not just a religion, it’s a lifestyle,” said Saynt. “Your friends, family and everyone you interact with are all Jehovah’s Witnesses.”

But at the age of 13, he had his first sexual experience with another boy from the neighborhood.

“It was very confusing and scary being in a faith that is so traditional in their approach to LGBT people,” he said of the church, which considers homosexuality a punishable sin. “It really stunts you.”

Saynt continued to seek out hookups with other men as well as women throughout high school, “but always kept it quiet and private.”

In 2001, against the wishes of his parents — who wanted him to become a missionary — Saynt enrolled at Berkeley College in Midtown.

“Once I was away from home . . . I was able to be more of my own person,” he said. He began experimenting, attending sex parties and using Craigslist to hook up with men and women. In 2004 he graduated with a degree in e-commerce and legally changed his surname to Saynt.

But he hid his true self once again when he married his now ex-wife in 2006 — and chose to keep his bisexuality and adventurousness from her.

The two were wed for six years before he came out to ­Alexander, with whom he had founded a digital lifestyle-marketing company, and the two went their separate ways.

This time around, he ­decided to make his passion for sex more than just a hobby.

‘I wanted to sell things that make people happy, like sex.’

“I got tired of selling shoes and handbags and beauty things that people don’t need,” said Saynt of his fashion-marketing days. “I wanted to sell things that make people happy, like sex.”

SAYNT began accepting applications for NSFW in 2015. Potential members must answer a detailed questionnaire about their fantasies and preferences, submit photos of themselves and provide links to their social-media accounts.

“We look for people with a story to share,” said Saynt. “If you can’t share a conversation with someone, you can’t share a bed.”

Saynt and his trusted “council” of five want people who post photos of themselves with friends and at local hot spots, doing fun activities and traveling the world. Hateful political views, too few photos or awkward close-ups are an automatic “No.”

“If a guy applies and says, ‘I just want to have sex with as many girls as possible,’ that’s not someone we want here,” said Saynt.

Attractiveness and savvy style are also big considerations.

“I use my bi[sexual] sense,” Saynt said. “Like, do I want to hook up with them? Would I want this person having sex next to me? If not, then we won’t accept them.”

“He’s basically creating a huge black book for himself,” one of his NSFW employees quipped.

Saynt and his club members believe high standards are what keep the sex parties sizzling.

“Being a hot woman, I don’t want to f–k everyone and I don’t want ­everyone to think they can f–k me,” said member Lola Jean, 28, who works as a sex educator and is known in the sex-club community as a wrestling dominatrix. “At other parties, it’s hard to be the hottest person in the room and have all this attention coming at you — but here, everyone is hot so they all get it.”

About 60 percent of members are couples in open relationships, and the majority are bisexual. The millennials say they are also happy to be among people who aren’t of an older generation.

“Sex clubs in New York have a feeling of age while you’re there and don’t feel new and fresh,” said member Mercedes Clark, 25, who works as a model.

THE bacchanals — the biggest of which take place at city venues such as House of Yes — celebrate themes ranging from BDSM and foot-fetish workshops to caviar dinner parties, but all end with little to no clothing on and plenty of hooking up.

“Members dress in layers to allow for various stages of nudity as the night develops,” said member Melissa Vitale, 25, a publicist. Sometimes there is a strict all-black dress code that includes masks.

“It’s an adult playground,” said Saynt, who now lives in the West Village with his longtime boyfriend. The two are in an open relationship.

At the Williamsburg clubhouse, the basement holds six beds with mesh dividers between them. Red Christmas lights and lanterns decorate each floor and a large “XXX” marquee sign greets people at the door. Photos of tattooed models holding pizza and hot dogs over their genitals line the walls. Black leather toys are on display for members to test.

Saynt’s marketing company, also called NSFW, works with brands such as Real Love Sex Dolls to market directly to club members by letting them test out and buy discounted products. The partnerships, in turn, help fund the parties.

During a recent gathering, Saynt — who is working on his strained relationship with his parents — and 15 of his closest members met to celebrate his birthday.

It was a milestone he was never ­allowed to commemorate growing up because of his religion.

But instead of blowing out candles for each year, Saynt spent an intimate night among his like-minded friends.

“It’s my way of making up for all the birthdays I didn’t have,” he said.

Additional reporting by Heather Hauswirth