The First Amendment says something about religion.
"but no religious Test shall ever be required as a Qualification to any Office or public Trust under the United States."
And even the 1st Amendment speaks of it as one of the freedoms to be protected. As Johnson himself has said, even Jefferson's Letter (to the Danbury Baptists Association) only speaks of our freedom to practice it without interference from the government.
Nowhere does the Constitution or the Amendments place restrictions on its practice.
Perhaps I should have been more precise in my original comment.
Yes it does. It is probably the most misquoted amendment too, because lefties like to try to make it something it is not. Congress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof.