The Supreme Court on Monday rejected an appeal from a former Marine who was court-martialed in part for expressing her Christian faith in the workplace.

Lower courts had concluded orders from her military superiors did not constitute a "substantial burden" on her First Amendment rights. The justices on Monday upheld her court-martial without comment.

At issue was the extent a federal law on religious freedom protects members of the armed forces like Monifa Sterling, who continued posting biblical verses at her desk, despite orders from a superior that she remove them.

The intersection of free speech on government property, especially within a military context, made this appeal closely watched by a number of advocates on both sides of the debate.

The First Liberty Institute, which represented Sterling, lamented the Supreme Court's call on Monday.

"Because the Supreme Court did not decide to review the case, the travesty below by the Court of Appeals for the Armed Forces will now stand," Kelly Shackelford, CEO and chief counsel for First Liberty, said in a statement. "The military court's outrageous decision means federal judges and military officials can strip our service members of their constitutional rights just because they don't think someone's religious beliefs are important enough to be protected. Our service members deserve better."

Sterling, who was a lance corporal stationed at Camp Lejeune, N.C., originally was court-martialed for various offenses relating to separate incidents -- including disrespecting a superior officer, disobeying lawful orders, and failing to report to an assigned duty.

But the part of the case that fueled her court challenge involved orders to remove a personalized version of the biblical phrase from Isiah 54:17: "No weapon formed against thee shall prosper."

Sterling taped the verses in three spots on her workspace. Court testimony said Sterling's superior repeatedly ordered her to remove the signs -- and when she refused, trashed them.

In its original 4-1 opinion, the U.S. Court of Appeals for the Armed Forces turned away Sterling's case.

"We reject the argument that every interference with a religiously motivated act constitutes a substantial burden on the exercise of religion," the court said.

Sterling was ultimately reduced in rank and given a bad-conduct discharge -- and later left the service. Her legal team acknowledged Sterling did not ask for permission to post or repost the verses but called the earlier ruling against her "shameful" and "wrong."

Fox News' Bill Mears contributed to this report.