Her life changed, Ms. Williamson said, after reading the Course as a young woman.

“Before the Course, I felt like I was on a desperate journey to find God, but as much as I climbed up this huge flight of stone steps in front of a cathedral, my knees bloody and my elbows bloody, the cathedral door was locked,” Ms. Williamson said. “And when I read the Course, I thought I understood the key.”

She soon sought out the book’s publisher, then based in the Upper West Side apartment of Judith Skutch, a maven of the city’s parapsychology scene. Ms. Williamson wanted to volunteer.

Ms. Skutch, now 88 and living in California, recalled a young Ms. Williamson bursting into her home looking “young and hungry for a path.” She said, “It felt like little firecrackers were coming out of her.”

In time, Ms. Williamson became a teacher of the Course in her own right. By the 1980s, she had relocated to Los Angeles to lead classes.

Around this time, the H.I.V. crisis was just beginning to take hold. Ms. Williamson formed groups for spiritual support, first in Los Angeles and then in New York City — she called them Centers for Living — and later, a meal delivery service for men with the disease. Studying the miraculous messages of the Course, she believed, could potentially prolong a person’s life. In her meetings, men were encouraged to focus on love and prohibited from using words like “death” altogether.

From the start, Ms. Williamson brought her own flair to the Course; her counsel could seem outlandish. “Imagine the virus that causes AIDS as Darth Vader and then unzip his suit and allow an angel to emerge,” she once advised.