With the U.S. Supreme Court expected to rule by the end of the month on whether same-sex marriage is legal, many Christian evangelicals say they would refuse to obey a decision allowing gay unions.
The Defend Marriage pledge, signed by more than 50,000 people, is one of a series of measures launched by social conservatives to push back against same-sex unions.
"The justices are not always right, and this is clearly a case that finds a right that is not in the Constitution, and we will not be able to respect that ruling," said Rick Scarborough, a prominent Baptist pastor in Texas and one of the authors of the pledge.
Scarborough says those who signed the petition will resist all government efforts to require them to accept gay marriage. He says some, including himself, will accept any fine, arrest or even jail time to protect their religious freedom.
"We respectfully warn the Supreme Court not to cross this line," Scarborough said.
Republican state lawmakers in recent months have introduced a raft of bills targeting gay marriage and gay rights amid expectations that the top U.S. court will find a constitutional right to same-sex marriage. It is now legal in 36 of the 50 U.S. states.
But of the 55 bills in 21 states that could have some bearing on gay marriage, the vast majority have failed to become law, indicating that any backlash to a Supreme Court ruling in favor of gay marriage could be limited.
The Defend Marriage pledge was launched in March by social conservatives. It says it is God's will to have marriage being only between a man and a woman.
"We affirm that marriage and family have been inscribed by the Divine Architect into the order of Creation. Marriage is ontologically between one man and one woman," it says.
Notable signers include U.S. Republican presidential hopefuls Mike Huckabee and Rick Santorum.
Same-sex marriage has been a tricky issue for Republican candidates with evangelicals a powerful force in determining the party's presidential nominee in 2016. But in the general election, a stance against gay unions could prove costly with polls showing a majority of Americans support them.
Some of the other signers are ready to launch a civil disobedience campaign, including trying to block county clerk offices that issue marriage licenses to same-sex couples.
Scarborough likened the fight to the campaign for civil rights launched more than a half-century ago by Martin Luther King Jr.
Adam Talbot of the Human Rights Campaign, at the forefront of the fight for gay marriage, says the comparison with King is blatantly wrong.
King, he said, fought for all Americans to be treated equally.
"It is deeply sad that a radical and small group of folks are so enraged by other people's happiness and legal equality that they are willing to plant their feet on the wrong side of history," Talbot said.
