I believe you are correct and when done as you suggest, one should not blink or falter to the very end, whatever that may be. I believe one should not threaten, defend or say a word but to repeat, “The letter is enough.” Stay strong and resolute and never quit. Make them fire you and state the cause in writing if possible.
It would be nice if such a letter were the means for “case closed” but a “sincerity” test of some sort is being applied. I have no idea how they are measuring “sincerity” of religious belief.
This is like the Spanish Inquisition. It defies belief that it is happening again.
The First Amendment does not have any provision for religious practice and freedom based on “sincerity tests”.
Refuse, Resist, Solidarity.
I have been saying for 10 months, “Biden is Hitler.”
Those words are being shown to be extremely accurate!!