Pilgrim’s struggle mirrors those of other congregations, of various faiths, across the country.

Richard Land, president of the Ethics and Religious Liberty Commission of the Southern Baptist Convention, said that over the last five years pastors had called him to seek advice about how to deal with sex offenders who had returned from prison and wanted to return to church.

The Rev. Debra W. Haffner, director of the Religious Institute on Sexual Morality, Justice and Healing in Norwalk, Conn., said she received one or two calls a month from congregations facing a crisis similar to Pilgrim’s.

Having a policy to deal with sex offenders before a crisis occurs is the best way to avoid turmoil, Ms. Haffner said. But such a policy still may force a congregation to decide under what circumstances an offender can attend, a discussion that can shake many churches to their core.

“They are conflicting ministries,” the Rev. Patricia Tummino said about reaching out to sex offenders, to children and to adult survivors of abuse. Since the late 1990s, Ms. Tummino’s congregation, the First Unitarian Universalist Society in Middleboro, Mass., has dealt with two known sex offenders. “You can’t be all things to all people,” she said.

Congregations have always had sex offenders, largely unknown to others, Ms. Haffner said.

Parole officers have encouraged offenders who have been jailed to seek congregations as a source of community and support, Ms. Haffner said.

States have computerized registries of sex offenders that let anyone check on a new congregant. Local news media often report on a sex offender’s arrival from prison, making it hard for a parolee to remain anonymous.

After being released in mid-2006, Mr. Pliska ended up at First Congregational Church, United Church of Christ, in Santa Cruz, Calif.

“My spiritual growth is very important to me,” Mr. Pliska said in an interview in Mr. Shockley’s office. “I went looking for an open and affirming church and attended a U.C.C. church and liked it.”

The United Church of Christ takes pride in its liberalism, and it has led other Protestant denominations in the ordination of women and on civil rights issues.

In Santa Cruz, Mr. Pliska agreed to avoid children and to always be escorted by another adult. The church has two services, which made it easier for those uncomfortable with him to still worship.

But business was slow and he lost his job as a mechanic, Mr. Pliska said, and in December, he moved to Carlsbad, an affluent seaside town 30 miles north of San Diego.

Mr. Shockley received an e-mail message from Santa Cruz about Mr. Pliska’s search for a new congregation. He said he thought that if Pilgrim established the same limits as Santa Cruz had, Mr. Pliska’s presence would be as uneventful.

Before introducing Mr. Pliska to the congregation, Mr. Shockley spoke to a few congregants who had been abused as children and to parents, and none objected to Mr. Pliska’s inclusion.

But Mr. Pliska’s introduction unlocked a flood of emotions among the 300 members.

“The scariest moment,” Mr. Shockley said, “was when I got the feeling in the congregation about whether Mark could attend or not, and we needed more time, yet people were saying ‘If he stays, I leave,’ or ‘If he leaves, I leave.’ ”

The church has pulled back from that edge, and most people seem to be listening respectfully to one another. A few families have stopped attending. Some new people have started to come, impressed by local news accounts of the congregation’s willingness to consider having Mr. Pliska.

Tristan Green attends with her three sons, and is torn about having Mr. Pliska in the congregation. She believes he should be welcome but she wonders how she might keep track of the boys during the social hour, whether they would enjoy the freedom to play, whether Mr. Pliska would get the church’s pictorial members’ directory.

“I’d feel uncomfortable,” said her oldest son, Sebastian, 9, “but we’re supposed to let everybody come.”

Samantha Peterson, 21, said she believed Mr. Pliska should attend. “I feel that those who are fearful have a very valid opinion, but we have a unique opportunity to be really tested and to make the right decision,” she said. “I don’t think this guy is a danger. He’s asking for help.”

Her mother, Missy Peterson, who also has a 10-year-old son, said she felt guilty about her wariness. But she could not ignore it.

“Why should I reserve judgment and not listen to the bells and whistles in my gut that say ‘No’?” Ms. Peterson asked.

Adult survivors of sexual abuse are also shaken by the possibility of worshipping with a sex offender.

“There are people who feel that if we don’t welcome Mark, we lose who we are,” said David Irvine, 48, who was sexually abused as a child. “But what do you say to one member who was abused for 10 years, several times a week? By welcoming one person, are we rescinding our welcome to some of the survivors among us, people in pain and healing, members of our family?”

An ad hoc committee at the church is trying to develop a “safe church” policy that would apply to sex offenders and would also create programs to prevent sexual abuse through education and screening of anyone working with children.

The policy is expected to be ready for discussion in early May, Mr. Shockley said. Mr. Pliska has been asked not to attend worship services for now, but he meets weekly with a small group from Pilgrim.

In the meantime, publicity over his arrival at Pilgrim led to Mr. Pliska’s eviction and the loss of his job. He is homeless and unemployed. Yet he said he does not regret being open with the church, after spending years hiding who he was.

“So far, there is no upside,” he said. “But there will be later on. God makes miracles in different ways.”