Each spring, a gala serves as the opening of the annual blockbuster show at the Metropolitan Museum’s Costume Institute. Hundreds of celebrities arrive in a frantic seasonal migration for that party.

This year, that exhibition is “Heavenly Bodies: Fashion and the Catholic Imagination” — and the choice of a religious theme gave a number of gala attendees a hot chance to tee off to the line of reporters on the event’s packed red carpet on Monday night.

“I’m a pagan,” said the actress Frances McDormand. “Aren’t you?”

“This is like my skin, I’m proud to be in it,” said Lena Waithe, the actress and writer, who was regally dressed in a black suit and cape that became a broad rainbow. “I’ve got the community on my back to make sure they know I’ve got them all the time.”

“The theme to me is like be yourself,” Ms. Waithe said. “You were made in God’s image, right?”

Not every outfit was political. “I’m the back wall of the Sistine Chapel,” said Ariana Grande, the singer, whose dress was a mass of papal conclave color. “I feel fairly important in this outfit, I have to say.”