This fall we will commemorate the 50th anniversary of the opening of Vatican II, pretty clearly the greatest religious event of the last century. In some ways the American contribution to the council is principally to be found in its Declaration on Religious Freedom, the handiwork of the American Jesuit John Courtney Murray, which solemnly affirmed: "that the human person has a right to religious freedom. This freedom means that all men are to be immune from coercion on the part of individuals or of social groups and of any human power, in such wise that no one is to be forced to act in a manner contrary to his own beliefs, nor is anyone to be restrained from acting in accordance with his own beliefs, whether privately or publicly, whether alone or in association with others, within due limits."

Now we are implicated in this battle over the HHS mandate concerning contraceptives, abortion-inducing drugs, and sterilization. It could've been another flashpoint. Denmark, for example, has just required churches to solemnize same-sex weddings. In Ireland, the government is seriously proposing abolishing the centuries-old priest-penitent privilege, thus enabling the government to force priests to violate the sacred seal of confession, something that has been well-settled in our common law since the days of Henry II and St. Thomas Becket. In Nigeria, in what seems like a weekly ritual, Christians are being killed for attending church.

How fortunate we are that we are not encountering any of these obstacles to living in accord with our consciences. Still, the threat to our religious freedom is real. When our government tells us we must pay for acts we believe and know to be immoral for everybody, our situation is comparable to what's happening in these other places, even if isn't precisely similar. So what are we called upon to do?

Of course, we want to render to Caesar the things that are Caesar's. But we must also render to God the things that are God's. Conscience, as the voice of God within, is distinctly a resident of Our Father's house. When the government tries to force conscience to bow to Caesar, we have no choice but to obey God rather than man.

When the authorities in Jerusalem ordered Sts. Peter and John to stop preaching about Jesus, they replied, "Whether it is right in the sight of God for us to obey you rather than God, you be the judges. It is impossible for us not to speak about what we have seen and heard." (Acts 4:19-20).

Note the context and the details. Peter and John didn't say the authorities were illegitimate. They didn't tell the authorities what they must believe. They even invited their listeners to judge for themselves according to their own consciences. But they stood their ground on one point: that they must do the will of God, no matter what anyone else--government included--says.

It's a bit of a Paul Revere moment. Only this time it's not the British that are coming. It's Big Brother. Or, if you prefer, think of Rosa Parks. We can go along and sit quietly in the back of the bus, or we can stand up for human dignity and the rights of conscience. When it comes to our precious heritage of religious freedom, we must either use it or lose it.

Dwight G. Duncan is professor at UMass School of Law Dartmouth. He holds degrees in both civil and canon law.