From the Area51 FAQ:
Should my idea be part of an existing site, or its own site?
In general, if a site makes sense as part of a bigger site, it's better to have one big site than a bunch of little niche sites. Site X should be subsumed by site Y if:
- Almost all X questions are on-topic for site Y
- If Y already exists, it already has a tag for X, and nobody is complaining
- You're not creating such a big group that you don't have enough experts to answer all possible questions
- There's a high probability that users of site Y would enjoy seeing the occasional question about X
Based on this (particularly points 3 and 4) it makes sense to me that any religion can have its own site. There are other religion based sites such as Christianity and Islam as well as proposals for Hinduism, Buddhism, Spirituality, and apparently even Satanism.