CHEYENNE, Wyo. (AP) -- A Roman Catholic congregation is being told that voting for pro-choice candidates in next week's election would be a mortal sin.

The Rev. Tom Cronkleton, of the Holy Trinity Catholic Church, said he has a moral obligation to remind his parishioners of their duty as citizens and as Catholics to vote for people who will represent them.

"There are five pre-eminent issues -- abortion, euthanasia, fetal stem-cell research, human cloning and so-called homosexual marriage," Cronkleton said. "How the candidates stand is a reason to vote for or against them."

In a bulletin insert on Sunday, Cronkleton said, "Being a Catholic sometimes is difficult, and being a Catholic voter is not an exception. We have to live by faith and moral principles and not by political affiliation or personal like or dislike."

He encouraged the congregation to stop by the church to pray before voting.

But at least one member of the congregation dislikes being told how to vote.

Joan Easley said at least one person walked out of the church during Sunday's sermon, and she would have walked out had she not been there with her 80-year-old mother.

"It was disturbing," she said. "I don't support abortion, but I also don't support going over and bombing and blowing up families either."

A lifelong Catholic, Easley said it is not the first time she has felt out of synch with the church's positions. But she said she has dealt with her disagreements quietly.

"They (the church) are the ones who have introduced me to the love of Jesus Christ, and I feel that they have the ability to give me the complete faith," she said.

"As far as the church doctrines, sometimes I have a problem with them. But you've got to suck that kind of stuff up."

But the language she heard Sunday was too hard to swallow. "They're actually putting their personal feelings on our religion," she said. "I don't think we should be judged on the personal feelings of a priest."

As a nonprofit organization, the church walks a fine line in its ability to speak to voters about the morality of their choices. The Internal Revenue Service does not permit nonprofit groups to endorse candidates or try to influence the outcome of an election.

A Roman Catholic pro-choice group based in Washington, D.C., Catholics for a Free Choice, has gone on the offensive against the archdiocese in Denver to try and halt its expressions of politics from the pulpit. The group is challenging the archdiocese's tax-exempt status.

"Non-profits can't get away with this by avoiding the candidate's name and using the word `pro-life,"' said the group's president, Frances Kissling. "There are two candidates -- one is pro-life and one is pro-choice. By saying to vote pro-life, they have said to vote for George Bush.

"If they say you cannot vote pro-choice, that is a statement of opposition, and that is illegal."

Information from: Wyoming Tribune-Eagle, http://www.wyomingnews.com