The parents of Messiah DeShawn Martin went before Tennessee Child Support Magistrate Lu Ann Ballew because they could not agree on the 7-month-old's last name.
Ballew instead last week ordered the baby's name changed to Martin DeShawn McCullough, the Tennessee television station WBIR reported.
"The word 'messiah' is a title, and it's a title that has only been earned by one person, and that one person is Jesus Christ," Ballew told WBIR.
Ballew, who could not be reached for comment on Sunday, said the child would likely struggle with his given first name because he lives in Cocke County, a predominantly Christian area in eastern Tennessee.
"It could put him at odds with a lot of people and, at this point, he has had no choice in what his name is," Ballew said.
Jaleesa Martin, the baby's mother, told WBIR she would appeal the judge's order.
"I didn't think a judge could change my baby's name because of her religious beliefs," Martin said.
Christianity refers to Jesus as the Messiah, while Judaism uses the term to mean an anticipated saviour of the Jews. Dictionary definitions say the word can mean one who is seen as, expected or professes to be a saviour or liberator.
Messiah was the 387th most popular name for boys born in the United States in 2012, based on applications for Social Security cards filed with the U.S. Social Security Administration.
In all, there were 762 applications for boys named Messiah in 2012, up from 368 applications in 2011