The mainstream Mormon faith had a collective freak-out this week over HBO's plans to show a sacred Mormon temple ceremony on Sunday's episode of "Big Love."

However, church members say, viewers hoping to glimpse strange religious rites will be disappointed. The temple ceremony is sacred, members say, but there's nothing particularly freaky about it.

Since 2006, "Big Love" has portrayed a fictional family of Utah polygamists, part of a religious group that split from the mainstream Mormon Church in 1890 when the church outlawed its practice of polygamy.

"Big Love" has always made Mormons squirm as it shares with Americans a piece of church history that members would rather not discuss. Also, the show often confuses the public into thinking mainstream Mormons are polygamists, which they are not. But this is the first time the show's revealing ways have taken on sacred tenets of the mainstream Mormon faith, the Church of Jesus Christ of Latter-day Saints.

"I am in shock that this is happening," says Patti Hull of Gilbert, a Mormon for all 60 of her years. "When you hold something sacred and people violate that, it's very disconcerting."

"Big Love" plans to show the Endowment Ceremony, one of many rites that take place within Mormon temples. During the ceremony, Mormons watch a video portraying the fall of Adam, make promises to obey church teachings and wear special clothing that they switch from side to side on their bodies. Only members of the Mormon Church "in good standing" are allowed inside, and most do not enter until they reach adulthood. Inside the temples, Mormons also promise not to discuss what happens within. However, when compared with the ceremonies of world religions in general, the temple rites will not seem strange, says Mormon Carmen Shelley, 50, of Gilbert.

"People will be greatly disappointed when this show airs," Shelley says. "These are pretty ordinary ceremonies that occur in every other faith."

However, Shelley says, "we hold (the ceremonies) sacred," and the public often mistakes this as secretive behavior.

"People seem to think there's something weird there because we don't discuss it openly," she says.

This week, while photos of "Big Love" actress Jeanne Tripplehorn wearing Mormon temple clothing circulated on the Internet, Mormons passed around furious e-mails calling for a boycott of the show and even America Online, which is owned by Time Warner, HBO's parent company.

The church issued a statement urging members to calm down, reminding them that such behavior would draw only more attention to "Big Love."

HBO representatives apologized in advance to Mormons who might be offended, saying the series' creators "took great pains to depict the ceremony with the dignity and reverence it is due," even consulting former church members. The details of the Mormon temple ceremonies are also available on the Internet.

Mainstream Mormons hope that "Big Love" producers won't latch onto the sacred rites of Mormonism as a permanent plotline or a way to boost ratings.

"The reason (the episode) is so upsetting to me it that it's not done in the right spirit," says Shelley, who plans to watch the episode to see if the writers got the ceremony right.

"It's not done to educate or enlighten but merely to entertain and to ridicule."