"How would the government be establishing a religion? And it specifically says Congress shall make no law...
I don't believe it discusses public education, does it?"
Do we really want to make the argument that the government can make rules for things restricting the constitution as long as it's only rules and not laws?
Should some government agency be able to make a rule banning guns or banning religion as long as it's not a law?
You would need laws that were constitutional, right?