In the US it does not matter. Freedom of Religion does not imply one must choose from a pre-approved list of religions.
0. https://www.irs.gov/charities-non-profits/churches-integrate...
But that also won’t use pre-approved lists.
There have to be some limits on what is allowed to be a protected religious belief. Otherwise we get into the realm of ranking which human rights matter more and that path leads to madness.
The path of "silly" religious beliefs is no better. My religion requires that Coke Zero be the one true soda. If the employee cafeteria offers sodas, you must accommodate my beliefs by serving Coke Zero. Also, Pepsi is the root of all evil and must never be allowed in the same room as Coke products.
If you truly believe that over-50s are against the will of <insert-deity>, then it is up to you to remove yourself when you hit that age.
Similarly, it is up to you to only consume Coke Zero and not be tempted by the evils of other sodas. If you feel strongly enough about it then you boycott any cafeterias that provide alternatives.
Religions that prescribe the behaviour of non-members are merely a means to control other people and such religions should be shunned by society due to the historical problems that they have caused.
My point is that those that hold religious beliefs would ignore limits if they targeted their beliefs anyway. Additionally, the action of defining what is and is not religion is usually done by those with self-righteous attitudes.
Humans regularly decide if they like someone based on what they believe and an unbiased definition will never be possible in our current state.
If I don't like Windows, and think maybe I could get out of it if I claim that it's against my religion, that's not a "sincerely held belief". It may be a sincerely held preference, but that's not the same thing.
If I have sincerely held beliefs that, say, closed-source software is immoral, and therefore it's morally wrong for me to use it, that's at least arguably religious.
The problem is to tell the two apart, especially when someone in the first category knows that they have to sound like they're in the second in order to pull it off.
Still, my point stands: Just wanting something, even wanting it strongly, and finding a way to wrap that in religious language, does not qualify for "freedom of religion" protection.
If a religion prevents a person from working on specific days, then that person shouldn't be forced to work on those days, but similarly, a workplace shouldn't be forced to employ them if they can't arrange a suitable compromise (e.g. they don't work Saturdays, but they can cover all the Sundays).
First Amendment
“Congress shall make no law respecting 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 to peaceably assemble, and to petition the Government for a redress of grievances”
IANAL but pretty sure that means we do have the "freedom to take any random thing you like and claim that it's a religion”