Fergie and hubby Josh Duhamel had their newborn son, Axl Jack (who was born back in August) baptized. The ceremony took place on Thursday, Dec. 12 in Los Angeles.

A source confirmed that the little guy was a perfectly behaved gentleman during the service, which took place at the St. Martin Catholic Church in Brentwood.

A witness said Axl didn't cry and that he looked handsome in his christening outfit. "Baby Axl wore all white and seemed very calm about being baptized. He didn't cry at all," the insider confirmed. He was minding his manners.

Mama Fergie matched her main man, as she also donned white for the ceremony.

It was a momentous occasion for the family. The source said they looked happy when they left -- which shocks no one, since it's a baptism, which is a big deal in an infant's life. Axl crashed out in dad's arms, which is the safest place a little tyke can be.

Congrats to Fergie, Josh and Axl on this milestone!