The issue of whether prayers can be recited before city hall meetings came under scrutiny at the US Supreme Court on Wednesday in a case that could affect the principle of separation between church and state.
Demonstrators on both sides of the debate gathered on the court steps as the nine-justice panel discussed the constitutionality of such prayers, and whether they amount to recruiting by Christians.
The case revolves around a dispute in the town of Greece in New York state, where local clergy are invited to come and give a prayer every month at the beginning of each city council meeting.
Two local women have challenged the practice, arguing it is unconstitutional and has no place in a political forum. One of them, Linda Stephens, is an atheist. The other, Susan Galloway, says that if prayers are said, they should be non-denominational.
They are being represented by an organization of Americans that pushes for separation of church and state.
Between 1999 and 2007, all the prayers were Christian. Since the women filed their first complaint in 2008, some prayers were recited by a lay Jewish person, a Wiccan priestess, and the president of a Bahai congregation.
Greece, which is backed by the US government, has countered that American history and tradition allows for prayers to be spoken in any legislative body, whether it is a small local assembly or the US Congress.
Wednesday's hearing got under way in a packed court which included many priests and nuns in the audience as the panel -- whose members consist of six Catholics and three Jews -- began examining whether the prayers violated the American constitution's cherished First Amendment.
The section of the constitution under scrutiny says Congress must not pass any law that grants institutional status to a religion.
Under the 14th amendment the clause is applied to the federal government, but also to local administrations.
Progressive justice Elena Kagan, who is Jewish, began the hearing by saying a Christian prayer and mentioned the sign of the cross, asking whether that would be "permissible" in a legislature.
"If it was constitutional in the past, why would it be unconstitutional today," remarked conservative justice Antonin Scalia.
"The people who are on the town board or the representatives of Congress, they're citizens... they should be able to invoke their divinity... when they're not judges or from executive branches," he added.
Represented by the organization Americans United for Separation of Church and State, plaintiffs Stephens and Galloway maintain that the prayers must be distinct from policy debates and non-denominational.
An attorney for the two women, Douglas Laycock, said any individual refusing to participate in a prayer at a town council meeting risked being unfairly judged.
"Citizens are asked to stand and those who are not participating are immediately visible ...irritating people you're trying to persuade," Laycock said.
Kagan meanwhile hinted that the court was reluctant to change existing practices.
"Part of what we are trying to do here is to maintain a multi-religious society in a peaceful and harmonious way," Kagan said. "And every time the court gets involved in things like this, it seems to make the problem worse."
Outside the court, atheist activists championed the women's cause, brandishing placards bearing slogans such as "There is No God in Government" and "Keep Your Theocracy Off My Democracy."
"We represent the 22 percent of Americans that are not affiliated with a religion," said Edwina Rogers, executive director of the Secular Coalition for America, a group which wants to do away with prayers during official ceremonies.
"The agnostics, atheists, and the free thought community, they do not have a seat at the table, they are discriminated against," she added.
"It is unacceptable based on our constitution."
Robert Boston, director of communications for Americans United for Separation of Church and State, said the case was "clearly an instance of government coercing people to take part in a religion as a price of interacting with local government."
"That simply is not right," he said.