Of the things Marilyn Monroe is best known for, being Jewish is not on the list.
But the impending sale of Monroe’s personal prayer book — or siddur, as it’s called in Hebrew — has piqued interest in the role religion played in the star’s cinematic life story.
Monroe is thought to have received the book after she married the playwright Arthur Miller and converted to Judaism. The book, labeled “Daily Prayers” on its spine, appears to have passed through the Avenue N Jewish Center, the synagogue Miller attended in Brooklyn.
“If it didn’t belong to Marilyn Monroe,” said Jonathan Greenstein, the president of the auction house that will sell the book on Nov. 12, “the book itself would be worth $50 to $100 — if that much.”
It had been estimated to sell for $5,000 to $8,000. But with the newfound buzz around the Monroe connection, it may go for up to $12,000, said Mr. Greenstein, whose auction house, J. Greenstein & Company, is based in Cedarhurst, N.Y.
Monroe and Miller were married in 1956 at a courthouse in Westchester County, according to a 2012 book about the couple, “The Genius and the Goddess.” Two days later, they had a religious ceremony, and a rabbi converted Monroe to Judaism.
Monroe once told the actress Susan Strasberg that she could “identify with the Jews,” according to the book. “Everybody’s always out to get them, no matter what they do,” Monroe said. “Like me.”
Others believe that Monroe embraced Judaism because it drew her closer to Miller’s family, especially considering she never had much of one herself. Because her mother spent time in and out of mental institutions and her father died in a motorcycle accident when she was a toddler, Monroe ended up living in a dozen foster homes.
Academics and museum curators have learned more about Monroe’s faith through letters from Rabbi Robert Goldberg, who presided over her conversion. In a 1962 letter to a scholar of Jewish history, dated a few weeks after Monroe’s death, Rabbi Goldberg wrote that Monroe had no religious training in her life apart from “some memories of a Fundamentalist Protestantism which she had long rejected.”
Rabbi Goldberg’s letter, excerpts from which were printed in Reform Judaism magazine in 2010, said Monroe admired the religion’s “ethical and prophetic ideals and its concept of close family life.”
Conversion to Judaism seemed to be a way for Monroe to gain healthier family relationships, said Joanna Robotham, a former curator at the Jewish Museum in New York.
Ms. Robotham, who organized an exhibition in 2015 about the Jewish conversions of both Monroe and Elizabeth Taylor, said the conversion of two of the world’s biggest celebrities was a source of pride for Jews — especially after World War II.
“It just showed that Judaism, coming off of the war, it wasn’t something people were trying to hide,” she said. “They were really celebrating Jewish culture and identity.”
After her marriage to Miller ended in 1961, Monroe is believed to have maintained her Jewish identity. She kept in her possession the prayer book and a menorah, which played the Israeli national anthem, until she died a year later.
Mr. Greenstein said the prayer book carried evidence of careful use. Notes in pencil have survived in the margins.
There is no definitive proof that the handwriting is Monroe’s, but Mr. Greenstein said he suspected it is. One indication is that “omit” is written next to a prayer involving a garment that is traditionally worn by Jewish men. Mr. Greenstein added that the handwriting could also be Miller’s or a rabbi’s.
In the decades since Monroe was found dead at 36, with an empty bottle that had contained sleeping pills on her bedside table, her former possessions have been auctioned off for hundreds of thousands of dollars to collectors and devoted fans. Two years ago, a wide-ranging trove was sold after a tour around the world.
Some of these possessions, like a miniature gold metal handbag with lipstick and cigarettes, reflected the life of glamour typically associated with Monroe’s superstar persona. Other items, like emotional letters about her struggles with mental health or the Jewish prayer book up for sale next month, offer a glimpse into the private life of a woman consumed by celebrity.