When the U.S. Supreme Court upheld Christian prayers at local government meetings on Monday, the justices wrote in exalted terms about balancing legislative prayer and religious neutrality. But two with opposing views were downright scathing toward each other in their opinions. Neither is known for pulling punches.

Conservative Justice Samuel Alito and liberal Justice Elena Kagan traded in more sarcasm than usual. At one point Kagan wrote, “That the (Alito) opinion thinks my objection … is ‘really quite niggling,’ says all there is to say about the difference between our respective views.”

Their quarrel underscored the difficulty of cases testing the line separating church from state in the U.S. Constitution and showed, more than customarily, how such disputes incite tensions, razor-thin votes and splintered opinions in a high court where all five justices in the majority were appointed by Republican presidents and the four in dissent by Democrats.

Rather than talking past each other from the tall mahogany bench, ignoring the other’s argument, these were written opinions that were joined, with each criticizing the other’s rhetoric and hypothetical scenarios. Opinions circulate among the nine justices after an oral argument, and usually people outside the court do not know how one justice has responded to another. With Kagan and Alito on Monday, however, their heated conversation was on public display.

Monday’s decision permitting overwhelmingly Christian prayers before council meetings in Greece, a town of 100,000 people in New York state, was written by Justice Anthony Kennedy.

“When the citizens of this country approach their government, they do so only as Americans, not as members of one faith or another,” Kagan wrote. She also warned her fellow justices against “government-sponsored worship that divides (people) along religious lines.”

Alito signed on to Kennedy’s opinion and then broke off to write a separate opinion, joined only by Justice Antonin Scalia, to make a stronger case for legislative prayer and denounce Kagan’s dissent.

“All that the Court does today is to allow a town to follow a practice that we have previously held is permissible for Congress and state legislatures,” Alito said. “In seeming to suggest otherwise, the principal dissent goes far astray.”

Kagan was joined in her writing by fellow liberal Justices Ruth Bader Ginsburg, Stephen Breyer and Sonia Sotomayor.

By virtue of their seniority, Justice Alito, 64, and Kagan, 54, sit side-by-side on the bench. They are friendly toward each other. But they are ideological opposites. Alito was appointed by President George W. Bush in 2006 and Kagan by President Barack Obama in 2010. Alito is one of the court’s six Catholics; Kagan one of its three Jewish justices.

Alito and Kagan accused each other of mischaracterizing each other’s views. Their differences were substantive as well as stylistic, and as the case reverberates across the country, their competing positions could shape how governments follow up on the decision giving them more latitude to mix prayer and government without violating the U.S. Constitution’s precept that government “make no law respecting an establishment of religion.”

Kagan took aim at the town council of Greece for failing to seek religiously diverse people to present prayers. The town was sued in 2008 by two residents, one Jewish and one an atheist.

“In arranging for clergy members to open each meeting, the Town never sought (except briefly when the suit was filed) to involve, accommodate, or in any way reach out to adherents of non-Christian religions,” Kagan wrote.

Alito countered that a town does not violate the Constitution “simply because its procedure for lining up guest chaplains does not comply … with what might be termed a ‘best practices’ standard.”

Kagan and fellow dissenters said the majority had taken a leap from the 1983 case of Marsh v. Chambers, which had allowed non-sectarian prayers in the Nebraska state legislature. That differed, Kagan wrote, from a smaller town council setting where individuals might attend to seek government assistance.

Kagan contrasted “morning in Nebraska” with “evening in Greece.” That prompted Alito to write mockingly, “it is more instructive to consider ‘morning in Philadelphia’,” referring to the locale of the first Continental Congress in 1774 where Christian prayers were delivered.

— by Joan Biskupic in Washington