At issue is whether the cross is a religious symbol or a piece of history that belongs in the 9/11 Museum.
American Atheists is appealing a ruling by the Southern District of New York last year that the cross and the 9/11 Museum "demonstrate how those at Ground Zero coped with the devastation."
"I lost my friend, Fr. Judge, the fire chaplain. I lost 10 other friends. This was a sign of consolation. It was never meant to hurt anyone, the atheists or anything like that," Fr. Brian Jordan, Ground Zero Chaplain, said.
But atheists say they were hurt. In court on Thursday, one lawyer said "the artifact screams Christianity"
He went on to propose a plaque be included in the museum that would read "atheists died here too."
"What we have here is a definite, consecrated religious object. It is not a historical artifact," Ken Bronstein, NYC Atheists, said.
But a panel of judges questioned what's the difference between a cross at the 9/11 Museum and religious objects at the Mets Cloisters in northern Manhattan? It includes all kinds of medieval religious objects.
A lawyer for the museum argued "rescue workers had a horrific experience (after 9/11)? They took some comfort in this object"
He also argued a plaque for atheists might sound nice, but it's not justified.
"The cross is a part of the story of 9/11. Museums don't' censor history, they don't' make up history, they tell history as it happened. And the cross is part of history. And the plaque is not," Eric Baxter, Beckett Fund Lawyer, said.