I've thought that before.
The government should get out of the religion business altogether. Just let free speech flow and everything will work out.
It's a lot easier NOT to have to deal with all of those court cases and all of those twists and turns. Just let everyone speak out full and free and the government will save a lot of time and energy.
If folks don't realize there are lots of different religions out there, then simply tell them to grow up. If they don't realize there are some religions with more members than others, then tell them to grow up.
I'm actually a deist, i.e. not fond of any organized religion. However, as long as no one is trying interfere (kill me or convert me), I'm content to let each practice his respective beliefs. People who have a problem with Nativity scenes, 10 Commandments displays etc. should really get a life.