WASHINGTON (RNS) Facing what they consider “threats” from American culture, prominent Catholic, evangelical and Orthodox Christian leaders are vowing unspecified civil disobedience against abortion, same-sex marriage and limits on religious liberty.

“We are Christians who have joined together across historic lines of ecclesial differences to affirm our right — and more importantly, to embrace our obligation — to speak and act in defense of these truths,” reads the seven-page “Manhattan Declaration.”

“We pledge to each other, and to our fellow believers, that no power on earth, be it cultural or political, will intimidate us into silence or acquiescence.”

More than a dozen Christian leaders — including Catholic bishops, an Orthodox priest, and officials of evangelical organizations — endorsed the document at the National Press Club. Organizers on Friday (Nov. 20) claimed about 150 initial signatories.

Archbishop Justin Rigali of Philadelphia cited increasing numbers of troubling incidents that he said sparked the new concerted approach, including doctors expected to refer or perform abortions despite their own objections, acceptance of embryonic stem cell research and assisted suicide, and the risk of marriage being “redefined in its very essence.”

“If someone asks, `Why now? What is the urgency of a declaration of conscience by Eastern Orthodox, Protestant and Catholic leaders?’, we say we must speak now because justice, which is love in action, demands that we not remain silent in the face of these threats,” Rigali said.

Supporters said possible civil disobedience would be up to individuals, but could include closing facilities or paying fines. Princeton University professor Robert George, a drafter of the document, said people need to be “prepared to make sacrifices,” just as the late Rev. Martin Luther King Jr. did when he faced jail during the civil rights movement.

The declaration specifically states initiatives to recognize same-sex marriage are not the “cause” of damage to the institution of marriage, which has been eroded by divorce and infidelity.

“What we don’t want to do is lock in any understanding of marriage that will become itself an impediment to us rebuilding the marriage culture,” said George, a Catholic layman and prominent ethicist.

Ronald Sider, director of the traditionally progressive group Evangelicals for Social Action and a signatory, said he viewed the document as “not partisan” but an embracing of Christian values.

“This is not a political ploy,” Sider said.

Several supporters said their concerns existed before President Obama took office last January, but the administration’s support for expanding embryonic stem cell research only enhances their need to speak up.

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Critics, including the group Americans United for Separation of Church and State, questioned whether the motives of the declaration’s supporters were ultimately political.

“I am optimistic that the people in the pews will not heed their leaders’ misguided call to action,” said the Rev. Barry Lynn, executive director of Americans United. “Polls show that most churchgoers do not want to see their faith politicized. But I am well aware that religious leaders have vast lobbying power that cannot be ignored.”