People can literally tattoo their faith on their foreheads, if that is what they want to do to proudly proclaim their faith, but using the car tags is a clear violation of keeping the church and state separate.
Hey South Carolina Christians, if you want to advertise your faith, is the only place left for you to do that is a license plate? How about your foreheads?
In a preliminary injunction, United States District Judge Cameron McGowan Currie ordered state officials to halt production, sales, advertising and distribution of the new license plates. The tags feature a cross superimposed on a stylized stained-glass window and the inscription “I Believe” above the tag number and the name of the state.
Associated Baptist Press - Judge halts Christian-themed South Carolina license plates