“Congress shall make no law 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.”
It’s definitely not as clear as one might expect out of a modern legal document. That being said, the precedent here is very straightforward, and any ruling in favor of the law would be a huge shift in how the separation of church and state is applied.