The fire broke out inside Saint-Charles cathedral, which is located in Saint-Étienne, France, at around 6pm on Friday night, police said.
Local worshippers present at the scene used holy water – in part – to put out the blaze, which did not cause any serious damage to the cathedral itself.
But the crib’s ceramic figurines were either damaged or destroyed in the fire.
Local investigators are currently searching for two arson suspects and said the fire could “not have been the work of one man” after finding two points of origin: one near the Christmas crib, and another near a statue of the Virgin Mary.
A group of local Muslims showed up at the cathedral on Saturday morning to show solidarity with Saint-Etienne’s “persecuted” Christian community, and offered to help clean up the scene, which was littered with ash.
Gaël Perdriau, the mayor of Saint-Etienne, strongly condemned the church attack, and said that the suspected arsonists had “desecrated a place of worship”.
Gilles Artigue, a local centre-right politician, denounced what he called an unprovoked “act of vandalism”.
But local priest Monsignor Bataille tried to appease residents who claim that the “xenophobic” attack was an “act of hate”.
He said: “A crib is a powerful religious symbol and the local Christian community has been shaken to its core. But the arsonists did not burn the cathedral to the ground. And, from what we have seen, they did not intend to cause serious damage.”