By Dan Merica, CNN

When Ron Johnson takes take his pulpit on Sunday, he will willfully break the law. After presenting his views on President Barack Obama’s handling of religious issues –- like abortion, gay marriage, and religious freedom - Johnson will ask his congregation a question.

“In light of what I have presented,” Johnson says he will say, “How can you go into that election booth and vote for Barack Obama as president of the United States?”

What Johnson plans to do is in violation of the IRS’ so-called Johnson Amendment, a 1954 law that has made it illegal for churches that receive tax exempt status from the federal government to intervene in “any political campaign on behalf of (or in opposition to) any candidate for elective public office.”

Why is Johnson so brazenly violating that law this Sunday? Strength in numbers: He will be joined by at least 1,400 others pastors across the United States.

Johnson’s sermon is part of a wider effort by the Alliance Defending Freedom, a conservative Christian legal organization that since 2008 has organized Pulpit Freedom Sunday, when they encourage and pledge to help pastors who willfully violate the Johnson Amendment by endorsing from the pulpit.

The movement is growing – and quickly. Pulpit Freedom Sunday had 33 churches participating in 2008, and 539 last year.

The goal: Force the IRS to come down on these churches so that the Alliance Defending Freedom, whose network includes 2,200 attorneys, can test the Johnson Amendment’s constitutionality.

“The IRS has the ability and the authority to regulate their sermons. We are giving them the opportunity to do that and if they challenge that, we will challenge that in court,” said Eric Stanley, Alliance Defending Freedom's senior legal counsel. “It is all about creating a test case to find the Johnson amendment as unconstitutional.”

With 31 days until Americans elect their next president, what is said at this year’s Pulpit Freedom Sunday could hold more sway than in previous years.

“I do think that the fact that it is an election year does make a difference,” Stanley said. “It is very relevant right now. Pastors who participate are speaking to something facing their congregation right at this moment.”

Johnson, who leads an evangelical church in Crown Point, Indiana, said he will not explicitly endorse Mitt Romney, the Republican challenger, but will vehemently challenge President Barack Obama, including calling the president’s policies “un-American.”

“As a pastor, I am going to tell it like I see it and I am going to communicate from the word of God,” Johnson said. “I hope that on Election Day, I hope that I have influenced people to protect their conscience.”

Critics charge that the movement is a Republican front dressed up as an exercise in religious freedom. When CNN asked to be put in touch with a church that plans to endorse the president, representatives from the organization said they don’t screen who the churches plan to endorse.

The two pastors that the Alliance Defending Freedom put CNN in touch with plan to either criticize the president or endorse Romney.

“I think there is a possibility that in some of these mega-churches, a pastor's saying it is OK to vote for Mitt Romney … could increase voter turnout,” said Barry Lynn, executive director of Americans United for the Separation of Church and State. “The ADF wants to elect the next president. They want to elect Mitt Romney.”

So far, the effort has received little to no response from the IRS.

After the sermons are delivered on Sunday, pastors participating in the Pulpit Freedom event are encouraged to send videos of their remarks to the nation’s tax collection agency. According to Stanley, the majority of the messages in past years have gone unnoticed and only a handful of pastors receive letters, some of which threaten to revoke the churches tax exempt status.

This trend of what some IRS watchdogs call nonenforcement has emboldened pastors and the Alliance Defending Freedom. According to pastors who have participated in the past, the fact that the IRS rarely if ever comes down on the churches emboldens them to keep endorsing.

Stanley and the Alliance Defending Freedom theorize that the IRS doesn’t want to be challenged in court and that the agency may be disorganized.

The IRS did not immediately respond to CNN’s request for comment.

Lynn and Americans United say that bureaucratic uncertainty as to what level of IRS official can initiate an investigation leads to lack of enforcement.

In the past, the IRS has investigated churches that they suspected of violating the Johnson Amendment.

Four days before the presidential election in 1992, the Landmark Church in Binghamton, New York, ran a full-page ad in USA Today that said, "Christians Beware," and that was followed by a list of Clinton's positions on homosexuality, abortion and the distribution of condoms. At the bottom, the church asked for donations to help pay for the ad.

According to Lynn, Americans United filed a complaint, and in 1995 the church lost its tax-exempt status.

Landmark Church Pastor Dan Little took the IRS to court, arguing that the agency was violating the church's First Amendment rights and that the agency was only able to revoke the tax-exempt status of a "religious organization," not an actual church.

Both a federal judge and an appeals court rejected those arguments.

When asked about people who question whether a pastor should be allowed to endorse from the pulpit, Johnson, the Indiana pastor, laughs.

“Pastors understand how the so called separation of church and state, as it is currently understood. We understand how marginalized we are becoming,” Johnson said. “We are supposed to be part of the community discussion about issues that matter.”