CULLMAN, Ala. — On a sofa in the hallway of his office here, Mitchell Williams, the pastor of First United Methodist Church, announced that he was going to break the law. He is not the only church leader making such a declaration these days.

Since June, when Gov. Robert Bentley, a Republican, signed an immigration enforcement law called the toughest in the country by critics and supporters alike, the opposition has been vocal and unceasing.

Thousands of protesters have marched. Anxious farmers and contractors have personally confronted their lawmakers. The American Civil Liberties Union and other civil rights groups have sued, and have been backed by a list of groups including teachers’ unions and 16 foreign countries. Several county sheriffs, who will have to enforce parts of the new law, have filed affidavits supporting the legal challenges.

On Aug. 1, the Justice Department joined the fray, contending, as in a similar suit in Arizona, that the state law pre-empts federal authority to administer and enforce immigration laws.

And on that same day, three bishops sued.

An Episcopal bishop, a Methodist bishop and a Roman Catholic archbishop, all based in Alabama, sued on the basis that the new statute violated their right to free exercise of religion, arguing that it would “make it a crime to follow God’s command to be Good Samaritans.”

“The law,” said Archbishop Thomas J. Rodi of Mobile, “attacks our core understanding of what it means to be a church.”

While church leaders have spoken out against similar laws elsewhere, Alabama is the only state where senior church leaders have gone so far in formal, organized opposition. But the law in Alabama, a state with an estimated 120,000 illegal immigrants, according to the Pew Hispanic Center, goes further than any other.

It contains some of the controversial provisions of other recent state laws, including one that empowers local law enforcement to try to ascertain immigration status after pulling people over for traffic violations.

But the law also makes it a crime to transport, harbor or rent property to people who are known to be in the country illegally, and it renders any contracts with illegal immigrants null.

To some church leaders — who say they will not be able to give people rides, invite them to worship services or perform marriages and baptisms — the law essentially criminalizes basic parts of Christian ministry.

Framers of the law say this is broadly exaggerated. The provisions, they say, clearly pertain to human traffickers or employers actively seeking to skirt the law. Churches, or people simply acting as Good Samaritans, were not intended as targets of the law, they say, nor would they be singled out in practice.

“It’s not as explicit as the churches would obviously like,” said State Senator Bryan Taylor, a Republican. “But I do not think that any church or any clergyman is subject to prosecution for doing their Christian mission.”

Transporting an illegal immigrant, lawmakers point out, is considered a crime under the law if it is done “in furtherance of the unlawful presence” of the person in the United States. “Harboring” an illegal immigrant is a crime only if it is done to shield the person from detection.

Lawyers for the church leaders contend that the language is far too vague to rely on such reassurances.

On Wednesday, Alabama’s attorney general asked the State Supreme Court to interpret the passages raised in the church lawsuit, which has been consolidated with two other suits, including the one brought by the Justice Department.

Leaders of the denominations represented in the suit are not the only ones with concerns.

An ecumenical group of ministers in Auburn has publicly condemned the law. Bob Terry, the president of The Alabama Baptist newspaper, wrote in a column that the state was trying to dictate Christian ministry.

Andy Heis, the pastor of the new, nondenominational Desperation Church in Cullman, said, “It puts you in a really, really hard place.”

“I understand legally where they’re coming from,” he said, pointing out that obeying government laws was a biblical command. “But spiritually, I have to do what God calls me to do.”

The politics of this are unusual, with those opposed to the law, mostly coming from the left, arguing that the statute falls short of biblical principles, and the law’s supporters, mostly from the right, arguing that secular laws and biblical law cannot always run on the same track.

And the politics are thorny for ministers, who acknowledge that the immigration law is broadly popular. Congregations are not in lock step behind their leaders.

Take Mac Buttram, a retired Methodist minister and a Republican who represents Cullman in the Legislature and voted for the law. Like other lawmakers, he insists that many of the law’s opponents misunderstand or exaggerate what it says.

Mr. Buttram also said he was surprised by comments from church leaders, including his own bishop, implying that those who supported the law were being mean-spirited and un-Christian.

“It’s a Christian issue, it’s a moral issue, but it’s not an issue in which we should be casting judgment,” he said, adding that several Methodist ministers had since called him expressing their support for the law.

State Representative Micky Hammon, a Republican and one of the law’s sponsors, said some church leaders had asked that a passage be included in the law that would exempt churches from certain provisions. But every attempt at writing such a passage ended up creating an unacceptably large loophole, he said, adding that any necessary adjustments to the law could still be made.

For some church leaders, the issue cannot be cut free of the weight of Alabama history.

The need for language forbidding racial profiling and the frequent failure by those discussing the law to distinguish between illegal immigrants and Hispanics in general give pause to opponents, even if they agree that current federal immigration policy is not working.

“Alabama needs to sit this one out,” said Bishop William H. Willimon, a Methodist who serves North Alabama. “The civil rights memorial in Birmingham is kind of a reminder that we’ve got to watch this sort of thing.”

An open letter to the governor and the law’s legislative sponsors, written by two Methodist ministers and signed by more than 150 other ministers, begins with a reference to the 1963 Letter From a Birmingham Jail by the Rev. Dr. Martin Luther King Jr., in which the civil rights leader rebuked liberal religious leaders, among them the predecessors of those who brought the lawsuit, for urging restraint in the fight against segregation.

The authors of the letter said they did not feel that they were making up for the clerical restraint during the civil rights years, but were simply drawing attention to Dr. King’s thoughts on unjust laws.

“King was saying context doesn’t matter — if it’s unjust, it’s unjust, and you call it like you see it,” said the Rev. Matt Lacey, whose Birmingham church was attended in the 1960s by Bull Connor, the city’s police chief and lead enforcer of segregation laws.

Mr. Williams, the pastor in Cullman, signed the letter but is less confrontational than some of his fellow ministers. For one thing, he thinks the church needs to be careful on how it speaks.

“I don’t think that the church can stand up and say a particular law is Christian or not,” he said. Still, he said, he has told his ministers to keep doing what they are doing, including the church’s active Hispanic ministry, whether the law is upheld or not.