From libertarian Michael A. LaFerrara:
The First Amendment prohibition that “Congress shall make no law respecting an establishment of religion” must be understood in its full context. The Framers understood freedom of CONSCIENCE as the foundational principle, and used “freedom of religion” and “freedom of conscience” interchangeably. Not everyone believes in religion or God or prayer. The government’s purpose is to secure every individual’s unalienable right to freedom of conscience, be they religionists, theists, deists, agnostics, atheists, people of faith, people of reason, believers in God, many gods, or no god, believers in “Fathers in Heaven,” or no Heaven.
It’s true that, as the article observes, “prayer isn’t [necessarily] religion.” But it IS a belief. The following “or prohibiting the free exercise thereof” means to be free of government coercion on behalf of anyone else’s beliefs. The government should never impose ANY belief system on anyone.