In Possible solution to frequent question closures, edits, migrations, and mission dilution at Biblical Hermeneutics: Floating the idea of a new site, GratefulDisciple provides an informative chart showing the differences between the related sites.
One big problem with these sites (and generally all SE sites) is that there is a very steep learning curve for new users. In particular, the site names often appear to be far more general than what they really are. For instance a site called "Christianity" is obviously the place to ask "Am I sinning when I …?", "Why does God …?", questions that are clearly off topic for those in the know.
SE is gamified. Much of it requires arcane knowledge, with individual users being rewarded with special privileges as they earn reputation (e.g. why else would the number of up and down votes for one's answer be hidden?).
For better or worse, this is how SE works, and it's not likely to significantly change soon.
New users waste their own time, and that of moderators and other users, going through the trial and error learning process. Many of them give up.
If there is to be another site, or even if there isn't, I'd suggest that the existence and purpose of all these sites be well advertised and well defined.
Currently, Christianity.SE begins with:
Like any library, Christianity Stack Exchange offers great information, but does not offer personalized advice, and does not take the place of seeking such advice from your pastor, priest, or other trustworthy counselor.
which is good to have, but it says nothing about the site itself.
Even less informative, Hermeneutics begins with:
Featured on Meta - Now live: A fully responsive profile - Reducing the weight of our footer - 2021 Community Moderator Election Results Hot Meta Posts - Why has my Reputation score suddenly changed?
I'd suggest that the Christian sites each begin with a common statement, something like:
Like any library, this site offers great information, but does not offer personalized advice, and does not take the place of seeking such advice from your pastor, priest, or other trustworthy counselor.
- Judaism.SE provides Biblical answers from a strictly Jewish perspective. Ask about the Tanakh (Hebrew scriptures), not about Testaments or anything specific to Christianity.
- Hermeneutics.SE provides objective answers about what the Christian Bible (Old and New Testaments) says and how it translates into English (exegesis).
- Christianity.SE provides objective answers about how a specific denomination interprets what the Bible and other texts say (eisegesis).
- BibleApplications.SE provides objective, possibly denominational, answers about how the Bible applies to the everyday lives of Christians.
Please be sure to ask questions on the relevant site, and to write answers that are worded appropriately for the site. (Questions or answers that contain "I", "me", etc. are almost always "off-topic".)
(I don't care about the specific wording or format; this is just an example of the kind of thing I'd like to see.)