The United States Conference of Catholic Bishops (USCCB) is calling on Catholics to “pray, fast and sacrifice” that the U.S. Supreme Court upholds two laws which define marriage as a heterosexual union.

The cases involved the Defense of Marriage Act (DOMA), which prevents federal agencies from recognizing the legal marriages of gay and lesbian couples, and Proposition 8, California's 2008 voter-approved gay marriage ban. The high court heard the cases in March and is expected to hand down rulings next month.

“A broad negative ruling could redefine marriage in the law throughout the entire country, becoming the Roe v. Wade of marriage,” the group wrote in a nationwide bulletin insert being shared with all U.S. bishops.

The bulletin's “lead messages” against marriage equality state that “sexual difference is essential to marriage,” “mothers and fathers … aren't interchangeable” and “redefining marriage in the law says [that] ... what adults want trumps what a child deserves and has a basic right to.”

The bulletin's reference to Roe v. Wade has become a popular mantra among social conservatives and is meant to suggest that instead of settling the issue, striking down the laws would create a tremendous backlash. However, the same could be said of rulings which uphold the laws considering that a majority of Americans support marriage equality.