The advice is especially useful in a nation becoming more diverse. Changes in U.S. immigration law during the 1960s allowed more non-Europeans into the country, increasing the presence of minority faiths.

"Clearly, there are dramatic changes that have taken place in our country in the last 50 years," said Stuart M. Matlins, a co-editor of "Perfect Stranger" and editor of companion guides for weddings and funerals.

While exact statistics are difficult to calculate, there are thought to be more than a million Hindus in the United States, at least several million Buddhists, and several million Muslims and Jews.

In Hawai'i, while the numbers of Jews, Muslims and Hindus are small, Buddhists outnumber even many Christian denominations, though that margin seems to be dropping as acculturation of Asian cultures continues to grow.

Even the nation's dominant faith, Christianity, is far from monolithic. Roman Catholics, Lutherans, Baptists and Episcopalians each have distinctive practices. In Hawai'i, Roman Catholics are by far the largest faith group.

Still, cultural collisions are unavoidable.

Albany resident Purdy, raised in a Christian home, went to synagogue in October with his then-girlfriend's family for Yom Kippur, the Jewish Day of Atonement, when he inadvertently stood for the mourning prayer. He realized his gaffe and sat down again quickly.

Purdy's interfaith philosophy is "if you're paying attention, you'll do OK." But the guides are for other people who want to make sure, or for the curious.

Kuehn, from Lakeville, Minn., was close enough to her Hmong friend to be one of those called upon to make a traditional toast around a big table at her wedding. She still wonders whether her all-English good wishes came across to the Hmong-speaking guests.

"I'm not sure if everyone understood me," she said.

More Americans are seeking help to clear up the cultural confusion.

"Perfect Stranger" went into its fourth edition this year and has sold more than 75,000 copies, Matlins said. Barnes & Noble is promoting the book for the holidays on the religion-themed tables in its stores.

"Multicultural Manners" is in its second edition and has sold more than 50,000 copies, said author Norine Dresser, who more recently wrote "Come As You Aren't! Feeling at Home with Multicultural Celebrations."

The books share retail shelf space with guides less concerned with interfaith how-to, but with explaining faiths like "Jewish Holidays, a Brief Introduction for Christians" or "Understanding Islam and the Muslims."

Authors say the books meet complementary needs — for people to understand their neighbors and for people to have their faith understood.

Consider the popularity of religious "open houses," events that give humanizing glimpses behind the doors of synagogues, churches and mosques. American Muslims, in particular, have been opening their doors with a sense of mission since the Sept. 11 terrorist attacks.

The Islamic Center of Long Island, which has been inviting people for many years, shows a 30-minute film on Islam and lets visitors watch prayers. Habeeb Ahmed, president of the Westbury, N.Y., center says the first five minutes can be a little tense for visitors, but they are soon at ease. If a female visitor lacks a head covering, "that is not a big deal."

That kind of flexibility seems crucial on the path to understanding.

Dresser mentions a widely distributed e-mail satire about a hapless human resource director who renames the Christmas party a "holiday party" to include Jews, then must accommodate Muslims fasting for Ramadan, a drumming circle for goddess worshippers, and so on until she is driven insane.

While it's not that extreme, Rensselaer Polytechnic Institute in Troy, N.Y., changed its staff Christmas party to a holiday party, and then finally to a year-end appreciation event.

Curtis Powell, vice president for human resources, said they take care to complement the Christmas tree with other decorations representing other faiths. And if they serve pork, it's on a separate table.

Dresser says it's hard to please everybody, though a little understanding goes a long way.

"I would still have the end-of-year party, and if there was a Christmas tree, no big deal," Dresser said.

"And if somebody wanted to put up a candelabra for Chanukah, that would be fine with me."

Advertiser religion and ethics writer Mary Kaye Ritz contributed to this story.