“While I do, in fact, ‘believe,’ it is my personal view that the largest proclamation of one’s faith ought to be in how one lives one’s life,” Mr. Sanford wrote on Thursday in a letter to Glenn F. McConnell, president pro tem of the Senate and a fellow Republican.

Image Design for a proposed license plate that Florida rejected in April. The new South Carolina law is for a similar plate. Credit... James Moore, Faith in Teaching, via Associated Press

The bill directs the Motor Vehicles Department to create the plate.

Mr. Sanford told the department to charge people just enough to reimburse the state for the cost to produce the plate, estimated at $4 to $6, and to not allow any organization to benefit from its sales.

The state offers 200 other specialty plates, supporting organizations like colleges, sororities, Boy Scouts and the Surfrider Foundation. The state charges up to $70 for those plates. The profit is sent to the sponsor.

A supporting organization normally pays the $4,000 start-up cost to create a plate. Because no organization will sponsor the “I Believe” plate, at least 400 people have to buy one before the state will produce it.

Representatives of the American Civil Liberties Union and the American Jewish Congress said they were considering suing the state over the plate. Neither organization was aware of any previous state that has approved a similar plate. A proposal for an “I believe” plate in Florida failed in April.