Based on some legal language I recall reading before it seemed to me that the standard was “sincerely held religious belief”. So the “traditional” may be a red herring. Note: I am not a lawyer.
Why would that make "traditional" a red herring? Whether the belief is sincerely held is a question of fact; the court is perfectly entitled to investigate it and examine evidence for and against, same as if they're deciding whether a killer sincerely believed the dead woman was trying to kill him when they're evaluating his self-defense plea. What, if a guy says he has a sincere belief that God wanted him to sell that crystal meth, the court is required to take him at his word just because he intoned the word "God"? A belief is a heck of a lot more likely to be sincere if it was taught to the defendant as a child by a community that's been teaching it to children for hundreds of years than if it's something he just made up himself, suspiciously synchronized with encountering a law he wanted to break.
Why would that make "traditional" a red herring?
Because
1) there is no consensus on what traditional means in an operative sense, and
2) it denies the legal validity of newly or “ nontraditional” religious beliefs that are sincerely held.
I.e., you snipped out my explanation and answered as though I'd never said it. The lack of consensus is immaterial since the judge/jury in each given case can simply decide; and of course it doesn't deny the legal validity of nontraditional religious beliefs that are sincerely held -- nothing of the sort.
In ruling on one of these cases there are two distinct questions a court has before it, and you persist in conflating them.
(1) Should we "accept that belief as a valid operational guide when we are dealing with social policy."
(2) Is the belief sincerely held.
You appear to be taking an attitude of "Question 1: No. Question 2: Who cares? See 1." As you put it, "So, of course, we can believe whatever they say the believe." Well, yes, we "can"; but that doesn't mean we
ought to believe whatever they say they believe. If we want, we can have our courts subject question 2 to normal standards of evidence and try to get correct answers instead of a one-size-fits-all answer good for nothing but letting us pat ourselves on the back about how accepting we are. If we want to actually find out if the belief is sincere, whether it's traditional is highly relevant. Not dispositive, obviously; but a traditional doctrine is more likely to be sincere than a newly made up ad hoc doctrine, so if the defendant wants to prove he isn't lying about a nontraditional belief he's going to need to produce stronger evidence.
As for why we ought to try to get a correct answer to 2, with respect to public policy, if we get correct answers then the magnitude of the problem of cutting believers some slack goes way down -- we'd only need to consider a few dozen sincerely held beliefs instead of the million-odd made-up fake beliefs people might offer as grounds for being exempted from some law. Of course if your goal is to make that problem as
big as possible in order to justify your "Question 1: No." attitude, then this isn't going to appeal to you; but we're a democracy and most Americans are in favor of cutting believers some slack and therefore have reason to make the problem as
small as possible. So doing what needs to be done to make that feasible helps make this the sort of country most of us want it to be. You're perfectly entitled to oppose that goal, but your policy preferences don't magically make "traditional" a red herring or magically make "traditional" deny the legal validity of nontraditional religious beliefs that are sincerely held.
You might not want it to be, but there it is.
