Leaders of religious organizations in the United States are calling on congressional leaders to craft legislation to protect schools from government discrimination based on their beliefs about the biblical definition of marriage.

More than 70 leaders in Christian education sent a letter to Senate Majority Leader Mitch McConnell, R-Ky., and House Speaker John Boehner, R-Ohio, this week to issue such appeal as they expressed growing concern about the possible implications of the Supreme Court's same-sex marriage decision later this month.

In their letter, the Christian leaders noted the exchange between Justice Samuel Alito and Solicitor General Donald Verrilli during the oral arguments on the issue in the Supreme Court last April. Alito asked Verrilli if universities that oppose the same-sex marriage concept could suffer the same fate that befell Bob Jones University which lost its tax-exempt status when the school opposed interracial marriage.

"It's certainly going to be an issue," Verrilli replied. "I don't deny that. I don't deny that, Justice Alito. It is—it is going to be an issue."

The implications of Verrilli's statement could be "far-reaching" for the nation's 29,000 religiously affiliated pre-schools, elementary schools, and high schools, not to mention the 1,700 religiously affiliated colleges and universities, according to heads of religious institutions.

The Christian leaders underscored that "majority of these institutions hold to religious traditions that forbid sexual intimacy outside of marriage between one man and one woman, and will not jettison these convictions for any tax benefit."

On Wednesday, Sen. Mike Lee, R-Utah, said he plans to re-file a bill that will provide protection for Christian learning institutions.

Lee told reporters in his Capitol Hill office that "The bill simply says federal government can't take adverse action against a religious institution based on that institution's belief in natural marriage. That's incompatible with our laws, that's incompatible with who we are as a people, and that's incompatible with our Constitution."

Lee said the bill's purpose is to codify President Barack Obama's 2013 promise that the government will not force religious groups to be in favour of same-sex marriage. The senator also noted that legislation has a much smaller scope than those state religious freedom laws that kindled controversy in the past months.

Lee filed a similar measure in the previous Congress. A House version of the bill secured 103 co-sponsors. He said the current legislation, which he plans to file next week, has been adjusted and will be given a new name.

The plan was announced by the senator along with four stakeholders: Jerry Johnson, president of National Religious Broadcasters; Samuel Oliver, president of Union University; Travis Weber with the Family Research Council; and Keith Wiebe, president of the American Association of Christian Schools, which represents some 800 faith-based K-12 schools.

Johnson asked if Christian radio stations would lose their licenses and Oliver wondered whether Christian students would still be eligible for federal Pell grants if they refused to believe and advocate same-sex marriage.

Oliver said if Christian schools are penalised by the federal government for their beliefs, "the consequences could be catastrophic." He said "the state system would not be able to handle the huge influx of students who would be forced out of the private system."

"To remove tax-exempt status from faith-based educational institutions because of their commitment to their beliefs about marriage would result in severe financial distress for those institutions and their millions of students," the Christian leaders wrote. "It would result in millions of students losing the choice of a faith-based educational experience that has been of historic value to the country for over 150 years."