The Girls star made the shock confession in his memoir Too Much Is Not Enough, which was released earlier this month.

In the book, Rannells, who was also nominated for a Tony for his role in the satirical musical The Book of Mormon, detailed his experiences as a student at a Jesuit high school in Omaha, Nebraska, which was run by priests, according to an excerpt published by Vulture.

Rannells recounts how a priest at his school, who he calls Father Dominic, who was in his 60s, had taken a special interest in him. At the time, Rannells believed that the elderly man had taken a shine to him due to his academic prowess.

The now openly gay actor admits that he was struggling with his sexuality at the time, and decided to “confess” to Father Dominic, as he had no one else to talk to.

“He seemed so strong, but so kind, and I was hopeful that he could save me from myself,” Rannells wrote.

He explains that during the confessions at his school, priests were in very close contact with parishioners. Instead of the a private room setup, “priests would set up two chairs close to each other in various darkened corners of the quad, turn on music at a low volume to muddle the sound of confessions, and then you would basically just get right up in a priests’ face and whisper your sins.”

After opening up to Father Dominic, Rannells wrote that the priest told him everything was “okay” and “hugged me tightly.”

“I felt safe and heard and understood. Then, with unexpected force, he kissed me. On the lips. He muscled his tongue into my mouth and held the back of my head still. Then he released me and made the sign of the cross on my forehead. He smiled,” Rannells wrote, adding that he “walked away, stunned.”

Following the incident, Rannells tried to avoid the priest for the rest of the school year, but was put in an awkward position when his mother suggested they invite him and several other teachers to a graduation party at their home.

Rannells alleges that Father Dominic ended up coming to the party, which is when he sexually assaulted him for a second time.

“At some point, Father Dominic needed to leave, and he asked if I could show him out,” he wrote. “We stood at my parents’ front door and said our good-byes for the final time, and then he grabbed me by the back of the neck and forced his tongue in my mouth. I just stood there and let him. I didn’t kiss back, but I also didn’t move. He smiled at me and walked to his car. I went into our kitchen and slammed a glass of wine before going back out to the party.”

It was then that the actor made the decision to leave the Catholic Church.