Child Support Magistrate Lu Ann Ballew ordered the name change last week, according to WBIR-TV. The boy's parents were in court because they could not agree on the child's last name, but when the judge heard the boy's first name, she ordered it changed, too.
"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.
It was the first time she ordered a first name change, the judge said.
Messiah was No. 4 among the fastest-rising baby names in 2012, according to the Social Security Administration's annual list of popular baby names.
The judge in eastern Tennessee said the baby was to be named Martin DeShawn McCullough, which includes both parents' last name.
The boy's mother, Jaleesa Martin, of Newport, said she will appeal. She says Messiah is unique and she liked how it sounded alongside the boy's two siblings - Micah and Mason.
"Everybody believes what they want so I think I should be able to name my child what I want to name him, not someone else," Martin said.
Ballew said the name Messiah could cause problems if the child grows up in Cocke County, which has a large Christian population.
"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," the judge said.