Congress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof At the time it was written, this clause originally applied to?

Answer: Federal law only

Explanation: As at the time When the First Amendment was drafted, the clause was originally applied only to the U. S. Congress (federal law only). As such, state government and local governments could also abridge the Free Exercise Clause, as long as they had no similar provision made in the state constitution ...