For historians seeking the original meaning of the Fourteenth Amendment, few issues are trickier than the question of national religious liberty. At the time of the Founding, the entire subject of governmental regulation of religion was left to the states. There was no single “principle of religious freedom” beyond widespread agreement that the federal government had no delegated authority over the issue. This left Virginia free to embrace the principles of Jeffersonian separationism and Massachusetts free to embrace the Adams-esque principle of semi-coercive, government-supported religious belief.
Adoption of the Fourteenth Amendment ended this freewheeling religious regulatory federalism and demanded that no state enact or enforce any law abridging the privileges or immunities of national citizenship.