With the Supreme Court's new session set to begin next week, all eyes are turning toward a religious hiring case that some are calling one of the most important church-state cases in years. The Washington Post previews Wednesday's argument:

One of the toughest questions facing the court, experts say, is whether the government should be allowed to decide which employee duties are “religious,” and which are not.

The high court has never ruled on the ministerial exception, and its decision will guide lower courts on whether to weigh more heavily the rights of religious institutions or their employees.

“I’ll tell you what makes this case really interesting,” said Lupu. “The last time the Supreme Court heard a case about internal church disputes was more than 30 years ago. This makes for a certain amount of unpredictability.”

“A new and narrow interpretation of the ministerial exception is certainly possible,” Lupu added. “That would alter employment relations in virtually every religious institution in the U.S.”

The Baptist Joint Committee filed a brief in the case urging the court to affirm a broad understanding of the  ministerial exception.