Blame it on Woodstock.

Cultural changes unleashed by the sexual revolution are affecting how millions of Americans understand religious liberty, according to University of Virginia law professor Douglas Laycock, speaking at a recent Newseum symposium marking the 20th anniversary of the Religious Freedom Restoration Act. It doesn't help that disputes about the free exercise of religion have increasingly turned into bitter partisan battles pitting Republicans against the majority of mainstream Democrats.

What is happening? It helps to remember that churches were on the winning side of the American Revolution, he stressed, and that fact has shaped America ever since.

"What if we had a new revolution in our time? The sexual revolution that began in earnest in the '60s carries on with the current front about same-sex marriage" and contraception, said Laycock.

Religious groups have consistently "been on the losing side of this revolution. … In each of the remaining sexual issues -- abortion, same-sex marriage, contraception, sterilization, emergency contraception -- every one of those issues has this fundamental structure: What one side views as a grave evil, the other side views as a fundamental human right. ... And for tens of millions of Americans, what religious liberty now does is empower their enemies."

Only 20 years ago, it was possible for left and right to find common ground on key religious liberty issues. The Religious Freedom Restoration Act passed unanimously in the House and by a 97-3 vote in the Senate, backed by a coalition that ranged from the American Civil Liberties Union to the Christian Legal Society.

Only five years later, another similar effort failed.

"We had gone from 97-3 to partisan gridlock ... and disagreement over religious liberty has only gotten worse since that time," Laycock told the Newseum audience. He was speaking the day after addressing the U.S. Supreme Court on yet another tense case about public prayer.

The key change, he said, is that there has been a violent legal and political clash between gay rights and the rights of religious conscientious objectors. At this point, it may be too late to find a compromise that would protect citizens on both sides of this constitutional firefight.

One crucial problem, he explained, is that conservative religious leaders have been "so focused on entirely defeating" same-sex marriage bills that they have paid little attention to religious-liberty exemptions "until they have been totally defeated and then, of course, it is too late. They have no leverage. They have nothing to bargain with."

Meanwhile, as the gay-rights cause has gained momentum, its leaders have grown increasingly bold. More than a few liberals, said Laycock, not only want to seize sexual freedoms, but to force religious objectors to affirm their choices and even to pay for them. Some on the left, he said, are now "making arguments calculated to destroy religious liberty."

Consider, Laycock said, language used by state Sen. Pat Steadman of Denver, as he fought for a civil unions bill in the Colorado Senate last February. What should liberals say to those who claim that their religious liberties are being violated?

"I'll tell you what I'd say -- get thee to a nunnery," he said, in debate recorded on the Senate floor. "Go live a monastic life, away from modern society, away from the people you can't see as equals to yourself. Away from the stream of commerce where you might have to serve them, or employ them, or rent banquet halls to them. Go someplace and be as judgmental as you like. Go inside your church, establish separate water fountains, if you want."

This was provocative language, but this gay leader was using arguments now common in American politics, said Laycock. "No living in peace and equality and diversity for him. If you are a religious dissenter you have to conform or withdraw. For many people this hostility to religious liberty is a growing and intuitive reaction."

It's too soon to predict the death of religious liberty in America, as it has been known and defended for generations, he said. But the current trends are sobering.

"Maybe compromise will prevail yet," he concluded. "Maybe the judges will do their jobs and protect the liberty of both sides. But the tendency of both sides to insist on a total win -- liberty for them and not liberty for the other side -- is a very bad thing for religious liberty."