A federal judge has ruled unconstitutional a Christian "I Believe" vehicle license tag with the image of a cross authorized last year by the S.C. General Assembly.

"The 'I Believe' Act's primary effect is to promote a specific religion, Christianity," U.S. District Judge Cameron Currie wrote in a decision released Tuesday.

State laws promoting one religion over others have been illegal in the United States since the nation's founding, Currie wrote.

Currie also focused on the role played by Lt. Gov. Andre Bauer, who originally pushed for the Christian tag after a move to create a similar "I Believe" tag failed in Florida.

"Such a law amounts to state endorsement not only of religion in general, but of a specific sect in particular," Currie wrote.

"Whether motivated by sincerely held Christian beliefs or an effort to purchase political capital with religious coin, the result is the same," she wrote. "The statute is clearly unconstitutional and defense of its implementation has embroiled the state in unnecessary (and expensive) litigation."

The tag in question would have featured a large cross against a stained glass window and the words: "I Believe." No tags had been issued. A state Department of Motor Vehicles spokesman said the department will abide by the judge's decision.