Good questions. Yes, a command to worship anything but God should be disobeyed. Yes, the constitution overrides all else (in theory) except We The People, and God. Yes, the 9th and 10th amendments say that the FEDs can't do what they do. Yes,
An early ruling of the Supreme Court clearly spells this out:
"An unconstitutional act is not law;
it confers no rights;
it imposes no duties;
it affords no protection;
it creates no office;
it is in legal contemplation,
as inoperative as though it had never been passed."
-- Norton v. Shelby County, US Supreme Court Decision 118 US 425, 442 (in 1886)