A judge dismissed a lawsuit on Friday that sought to stop the display of a cross-shaped steel beam found in the World Trade Center’s rubble, saying it could help tell the story of the terrorist attack.

The judge, Deborah A. Batts of Federal District Court in Manhattan, rejected the arguments of the nonprofit group American Atheists, which filed a lawsuit against the operators of the National September 11 Memorial and Museum in 2011 on constitutional grounds, contending that the prominent display of the cross constituted an endorsement of Christianity, diminishing the contributions of non-Christian rescuers.

Judge Batts wrote that the cross and its accompanying panels of text helped “demonstrate how those at ground zero coped with the devastation they witnessed.” She called its purpose “historical and secular,” and noted that it would be in the “Finding Meaning at Ground Zero” section of the museum, with placards explaining its meaning and the reason for its inclusion.

“No reasonable observer would view the artifact as endorsing Christianity,” the judge said. She added, “The cross does not create excessive entanglement between the state and religion.” She said the plaintiffs also failed to find any form of intentional discrimination or cite any adverse or unequal treatment on the basis of their religious beliefs.