You might want to actually read the first amendment:
Congress shall make no law [emphasis added] respecting an establishment of religion, or prohibiting the free exercise thereof; or abridging the freedom of speech, or of the press; or the right of the people peaceably to assemble, and to petition the Government for a redress of grievances.
(In various ways that aren't very relevant to the current discussion, this generally applies to states as well.)
