The Archdiocese of Washington is suing Metro for rejecting this ad. Metro says the poster violates its policy banning ads that “promote . . . any religion, religious practice or belief.” (Archdiocese of Washington)

A federal appeals court on Wednesday denied a request from the Archdiocese of Washington to temporarily block a lower-court ruling that has kept its Christmas ads off the sides of Metro buses this holiday season.

In a four-page order, three judges for the U.S. Court of Appeals for the District of Columbia made a preliminary determination that Metro officials were well within their rights to prohibit the archdiocese’s proposed posters in accordance with the transit agency’s ban on ads that “promote . . . any religion, religious practice or belief.”

The advertisements in question featured an image of three people walking with sheep and holding shepherd’s staffs — assumed to depict a scene from the biblical story of Christmas — and included a tagline, “Find the Perfect Gift,” which referred to an archdiocese-sponsored website that encourages people to attend Catholic Mass or donate to charitable organizations during the holidays.

The Archdiocese’s lawyers contended that church officials had been victims of viewpoint discrimination, and that other commercial entities or charitable organizations were allowed to use ads on Metro that mentioned spirituality or religious holidays.

But the appeals court judges, Judith W. Rogers, David S. Tatel and Patricia A. Millett, said that argument was “grounded in pure hypothesis.”

“Appellant [the Archdiocese of Washington] has not come forward with a single example of a retail, commercial, or other non-religious advertisement on a WMATA bus that expresses the view that the holiday season should be celebrated in a secular or non-religious manner,” the decision said.

The three-judge panel emphasized the “preliminary nature” of its findings and said the order does “not speak to the ultimate merits” of the broader challenge.

But it does mean that the Archdiocese will not be able to place its ads before Christmas. The court said oral argument in the case would be set sometime after mid-February.

The appeals court action is the latest development in a lawsuit filed last month by the Archdiocese of Washington, which argued that Metro’s decision to block its advertisement from appearing on public buses was a violation of the right to free speech and religion.

Metro denied the Archdiocese’s request to post the advertisements on the agency’s buses, citing internal guidelines barring ads that are religiously themed. The agency says its ban on such content is part of an effort to keep away incendiary material that could incite violence.

That argument got a little more traction last week, when the New York City subway system became the target of an attempted terrorist attack, conducted by an alleged supporter of the Islamic State. According to the New York Times, 27-year-old Akayed Ullah later told investigators that he chose the subway as his target in part because of the Christmas-themed posters present on the system.

But in its original lawsuit against Metro, the archdiocese pointed out that plenty of other ads on the transit system are Christmas-themed. The difference, they pointed out, is that those ads are sponsored by corporate entities.

“If Christmas comes from a store . . . then it seems [the Washington Metropolitan Area Transit Authority] approves,” archdiocese spokesman Ed McFadden said at the time of the original lawsuit. “But if Christmas means a little bit more, WMATA plays Grinch.”

In its lawsuit, the Archdiocese cited instances in which Metro allowed ads for a yoga studio — ads that promoted a “spiritual” practice, the church’s lawyers argued — as well as ads for the Salvation Army’s holiday “Red Kettle” giving campaign. The Salvation Army is a Protestant organization.

Earlier this month, a U.S. District Court judge sided with Metro and denied the Archdiocese’s request for an injunction that would force Metro to post the ads. The archdiocese immediately appealed, but the U.S. Court of Appeals took the same stance as the lower court.

The problem with the archdiocese’s ads is not simply that they appear to refer to Christmas, the appeals court judges said, but that they are promoting religion.

“Appellant references a CorePower Yoga advertisement, but that advertisement contains no discernible holiday, seasonal, religious, or irreligious content,” the trio of judges wrote.

“Appellant also points to a WMATA-permitted Salvation Army advertisement encouraging donations to its seasonal Red Kettle campaign so that funds can be used to help the less fortunate,” they continued. “That advertisement underscores, however, that WMATA does not exclude religious speakers from advertising when their proposed messages comport with the allowed categories of speech,” including donating to the poor.

In a statement, McFadden did not rule out the prospect of further legal action against Metro.

“We are disappointed by the court’s decision to not provide an emergency injunction, but will review next steps to ensure that regardless of the season, the Archdiocese of Washington can share and express our faith and serve the most vulnerable among us in the public square,” McFadden said.

Ann E. Marimow contributed to this report.