Her plans for a life of poverty, however, went awry when she married at 17 and began writing at age 19. Steel has since sold more than 560 million books and on Tuesday will publish her 72nd novel "Honor Thyself." "I wanted to be a nun when I was young," Steel, 60, whose success has made her a regular on the New York Times bestseller list, told Reuters in a rare interview. "Religion is what keeps me going, I would be utterly lost without it."

Steel's life is quite a contrast with the vows of poverty, chastity and obedience taken by nuns. She has been married five times, has seven biological and two adopted children and splits her time between homes in San Francisco and Paris. But while she didn't choose to become a nun, religion has remained a strong part of her life.

"I was brought up a rabid Catholic and there have been times -- like when my son died and my (fourth) husband had left me -- I went to mass twice a day just to hang on," she said. "It's a very present support system for me." "It's not for everybody but it works for me," she said. Steel said she also used her writing as a refuge when her son Nicholas Traina committed suicide just over a decade ago at the age of 19. Traina had bipolar disorder, characterized by abrupt mood swings.