That doesn't imply that there aren't some limitations on your activities.
As a Christian I find a lot of non-Christians always asking “why must ____?”
Do you think it is just non-Christians who ask that?
To me, it comes off, and most often is, when you dig beneath the surface, a way to squash and suppress the Gospel.
Nonsense. Now this may come as a shock to you, but some of us simply want to get on with things without being stopped on the public streets and bothered by people trying to push their beliefs down our throats.
There are many who would try to corral it to just inside four walls of a building. That’s not going to happen.
Evangelists have the right to use the television, radio, and the Internet to get their message out. They can rent open land and even a stadium and gather there. Like anyone else with something to say, they can speak in the parks that have dedicated 'speakers' corners', providing the rest of us can sit or play peacefully without being approached.
I don't want to be accosted while I'm riding on public transportation, or stopped on the street, or approached when I take the kids to the park. We citizens should have the right to use the public facilities we pay for without those facilities being turned into venues where we are fair game for anyone who has decided to spent a few hours proselytising.
Whether or not someone is a Christian is none of anyone else's business, unless that person chooses to divulge that information. Whether some evangelical approves of the denomination individuals choose to follow doesn't interest most people. People have a right to be left alone with their thoughts.
I have no problem with the idea of the plates because I would avoid anyone who would choose to have them. If people want to call attention to themselves to emphasise their holiness, they look like phonies to a lot of people.
However, unless other denominations/religions get the right to choose vanity plates that hype their faith, the state is practising favoritism. How do' Follow Baha'i' and 'Believe in Buddha' look to you?