Andra Day’s connection with God helped her in her performance in The Redemptionshe tells PEOPLE.

In the new horror film directed by Lee Daniels, the 39-year-old actress and singer plays Ebony Jackson, an alcoholic single mother who struggles to support her three children and her own mother Alberta (Glenn Close), with whom she has a difficult relationship.

After moving to a new house, Ebony’s children become possessed by demons – and she must seek help from the religious world she had long since avoided.

In one of the climactic scenes, Ebony calls on Jesus while battling a demon and begins speaking in tongues while praying. In this moment in the film, Day was actually praying, which allowed her to actually speak in tongues – that is, she recited an unknown language in what she describes as “an act of worship.”

“I don’t know how to explain it, but speaking in tongues is like speaking in a heavenly language,” explains Day, who says she doesn’t do it “all the time.”

This is something the Oscar-nominated star, who won for his performance in The United States vs. Billie Holidayshe says she has learned throughout her life.

“When I was younger, I was really scared and uncomfortable with it,” recalls the San Diego native, who remembers going to her friend’s house as a child and seeing her mother speaking in tongues. “I just thought, ‘This is crazy.'”

“But then I got older and my relationship with God got stronger and stronger. I was reading about speaking in tongues. I read about a pastor who was also struggling with it. He said it was very strange for him and he focused on it daily,” she continues.

“I remember telling God, ‘I want that closeness to you. I want that heavenly language.’ So I kept going and going. It still felt weird, it felt weird, felt weird for a year. Then finally, one day, I really felt the Spirit take over. Then it was like, ‘Wow,'” Day says.

“I would get clarity in that area,” she says. “I would just hear things about what I should do, what people I should work with, where I should work.”

Day says she didn’t want to act out the scene, but rather pray and “just let it happen,” she says. Daniels agreed. “Of course he said, ‘This is what I want.’ It has to be authentic.”

At one point while she was filming the scene, producers wondered if they should stop her. “And Lee said, ‘No, just let her go.’ Lee had the foresight to capture it.”

The Redemption hits theaters today and will stream on Netflix on Friday, August 30th.

For more on Andra Day, pick up the new issue of PEOPLE.