Now, I fully believe in the Constitution. This includes the first amendment. This amendment allows people the right to freedom of religion, meaning they can worship, or not worship, as they see fit. It also means that the state would not endorse any specific religion.
So, unless Fischer is so unpatriotic and unAmerican as to want to willfully violate the Constitution (even though he probably is), I am sure he won't mind a license plate for those that practice Islam:
or for those Devil Worshipping Atheists:
Mixter has other suggestions for license plates over yonder.