Join the club. All you need is faith, in God and each other.

The Faith Club, published late last year by Free Press, is a response to the Sept. 11, 2001, terrorist attacks. It’s subtitled A Muslim, A Christian, A Jew – Three Women Search for Understanding.

And they find it.

Ranya Idliby, Suzanne Oliver and Priscilla Warner, the authors and residents of New York who didn’t know each other before this book project, discover their religions have more in common than they knew. The most basic shared tenet is this: Be nice. Love your neighbor as yourself.

“Some people are afraid to experience other religions because they’re afraid it will dilute their own faith,” says Warner, a Jew who grew up in Rhode Island. “But beauty is where you find it.”

On Sept. 11, 2001, Warner found her faith dashed.

“I was lost spiritually,” she writes. “I wasn’t sure if I believed in God anymore.”

Then, through a friend of a friend, Warner entered The Faith Club. Idliby, a Muslim, came up with the concept. She wanted the world to know her religion was different than the one that guided the terrorists. She wanted to find a Christian mother and a Jewish mother. Together, they would engage in an ongoing comparative religion discussion that would produce a children’s book.

Idliby met Oliver at their children’s bus stop. Warner, a children’s book writer, came to the club by referral.

“We were on a mission to figure out if the three religions could co-exist peacefully,” Warner says. “If we couldn’t resolve that, there was no hope for our children. That’s what kept us coming back. I wanted to bring my children hope, but really it was to bring me hope. I didn’t realize how lost I was until I was found.”

The women met regularly for two years before creating a book, which is not for children (although that book is still planned), but for adults, about the women’s shared experience of coming to an inter-faith understanding.

Efficient the process wasn’t. None of the women was expert in theology.

In the book, Oliver, a Christian, admits that in preparation for her Faith Club meetings she purchased two books: The Complete Idiot’s Guide to Understanding Judaism and The Complete Idiot’s Guide to Understanding Islam.

“I figured I had to start somewhere,” Oliver writes.

On occasion, the women did seek the advice of religious experts: a priest, rabbi and imam. But the women’s opinions in the book are their own, those of common lay people.

“There was a sense of urgency after 9/11,” Warner says. “We couldn’t sit around and wait for clergy to figure it out and hand it down to us. We couldn’t wait for them to tell us what we had to do. We had to take things into our own hands.”

They weren’t alone, according to Warner. There were many so-called faith clubs before 9/11, and more after.

“We are now part of a movement,” she says.

The idea of seeing the world from different religious perspectives was part of Warner’s upbringing. She attended the Providence Hebrew Day School, which in the book she describes as “an exotic, insular experience, where I began to think the earth was primarily populated by Jews.”

Then, in high school, Warner’s late father entered her in the all-girl Lincoln School in Providence, a school with a Quaker tradition.“I suppose he sent me to what he felt was the best school in the area,” Warner writes. “While my father was proud to be a Jew, he was a Jew on his own terms. Sometimes he fasted on Yom Kippur; other years he didn’t. On some Passovers he ate no bread; other years he started the day with an English muffin.”

In the Quaker school, Warner sang hymns and participated in prayers.

“The Quakers have a wonderful philosophy about social justice and religion, and not proselytizing,” Warner says. “They had prayer meetings where people could say whatever was on their minds.”

This was the essence of The Faith Club. The three women talked about traditions and rituals, stereotypes and misconceptions of each other’s religions.

“One of the most important components of the book is that we were all strangers to each other,” Warner says. “I think if we were friends, we would have tip-toed around issues.”

Religion can be a sensitive subject, Warner says. Thoughtfully questioning it — your religion or someone else’s — can be difficult, which is why many people don’t.

“I want to hide under the covers some days,” Warner writes. “Why can’t I sit back and worry about Britney Spears’ belly button, like millions of other Americans do? On some days, that sounds like a plan.”

As a result of her exposure to one Muslim woman and one Christian one, Warner says she has redefined her notion of God.

“Before, God to me was an eternal protector. I had a very selfish idea of God. It was as though I had a global positioning device on me. ‘Oh, she’s on an airplane.’ Or, ‘She just made a right turn off the highway.’  ”

Now, Warner says God is simply what is good in the world and what is good between people.

“It takes more courage to be a dreamer than a cynic,” she says. “We are living in cynical times. People are hungry for something else.”

Perhaps that spiritual hunger can be satisfied with Judaism. Or, as Warner has found, it can also be satisfied with aspects of other religions, whether it’s the element of humility underscored in Islam, or the teachings of Jesus in Christianity.

“Jesus means a lot to me now,” Warner says. “Who would have known? This is a woman who took down a crucifix in a hotel room. I didn’t want to sleep under a dead man who meant nothing to me.”

Not only does each of the three religions offer something of value, Warner says, but each focuses on the same central message: love one another.

This is the message Warner and the other Faith Club members deliver on their book tour.

“People say ‘What you’re doing is great, but you’re preaching to the choir,’  ” Warner says. “I say, ‘Yes, but the choir isn’t singing loud enough.’ I definitely think there is a silent majority out there.”

For more information, visit www.thefaithclub.com.