The tag "bible" seems overly general to me (much the same way the tag "john" is too general)
Wait a minute... john isn't too general - it's ambiguous! There are multiple Johns. If you were arguing that we need multiple bible tags because there are multiple bibles, this would be a good comparison, but you don't seem to be worried about that.
Tags are a "folksonomy" not a hierarchy
Please resist the urge to create an unnecessary hierarchy in the naming of tags, or create tags that are excessively specific. Unless history would mean something completely different when paired with bible than when paired with, say, law, there's no need for this. You can let the tags stand alone, apply them when needed, and let the system give you bible history and law history questions.
Same thing goes for interpretation. Combine it with bible or catechism or apocrypha or whatever to give it context.
You can have up to five tags on any given question. Make 'em count...
Tags are for describing the content of the question
Along these same lines, be careful about using or refining a tag in such a way that it becomes a meta-tag: do you really need
*-reference tags, when the primary purpose of this site is to create reference material for future readers? What does adding
*-reference to a question tell you that simply seeing the question on the site does not? It feels like you're asking for [bible-reference] to avoid having a plain ol' [bible] tag...
Tags are almost never used properly by question authors anyway
If the folks asking questions on this site are consistently picking a perfectly applicable and comprehensive set of tags when asking, it'll be the first site on the network where that's happened. Let's face it: proper tagging is almost always a result of dedicated retaggers - editors - not conscientious authors. So when designing a set of primary tags, it's the editors who are your audience.
If you can get the asker to pick one good tag, you're doing pretty well... So there's some serious temptation to make tagging extra-difficult for the asker, in the hope that he'll put more thought into it...
"Oh, the obvious choice for tagging biblical questions is "bible" - if that's not available, they'll have to choose "bible-something" and we'll get two good tags!"
--deviously clever taxonomist
Best part of this is, it works! ...sorta. It works if there are only a few choices, and they're good choices, and those are the only choices you could possibly have. Which again, is probably why you stuck "bible-reference" in there, since that's pretty much a superset of any other [bible-*] tag.
But you're not doing anything for the editors, who now need to worry about whether they should add a second clarifying tag (
[bible-reference] [health]) or create a new hierarchical tag (
[bible-health]). And you're not doing anything for the reader who's looking for history questions and can't get them by just clicking on the tag name, and then refining.
Worst of all, you're throwing away one of the biggest advantages of tagging: it's organic. You don't have to memorize some complicated hierarchy to make it work; just describe the question in simple terms, and let the system worry about the rest.
Conclusion: pick good tags, not complex tags
Let me return to the john example you led off with. This is an obvious but ambiguous tag; if we rely purely on organic tagging to define it, we'll quickly find it used to mean multiple things. So something needs to be done. That doesn't necessarily mean banning the tag; it simply means we need to set the system up (via synonyms, wikis, etc.) to where its use is unambiguous.
bible should be fairly unambiguous. We might need or want clarifying tags at some point, to indicate specific translations... But those simply help to better describe the content of questions on which they're applied, and probably do not need to used in all cases. And yes, it will probably end up being a fairly popular tag, simply because of the nature of the site... So we'll want to make sure it's not used on questions where it doesn't apply. But the solution isn't to mangle it, or dispatch it entirely in favor of some hard-to-understand hierarchy.
It's a good tag - use it. And use it well. Create other good tags, and use them well. Let them be fruitful and multiply and fill the site...