Wow this is why I do not want to go to FL

Because the DMV/BMV is a government institution?

They didn't float the idea either.

It passes all the guidelines implemented for new plates. Just because it has religious intentions doesn't automatically violate church/state separation. You're ALLOWED to be religious in this country...
 
IIRC we had a similar sitch in MI where some RWNJG wanted to put out a WWJD plate...

They were roundly rejected by the state govt.

I can't speak for MI, but maybe they wrote it to limit religious plates or something. In Florida, there is no such limit and therefore the plate should be allowed.