Neal, I really like your most recent proposed wording above, and I think defining the term as a religious belief is a good solution.  We really need to get away from the "X is the ability to do Y" wordings that we've had, and this is a fair way to do it.  Part of the problems these articles have had is that they try to cherrypick different elements from religious and scientific views, mixing and matching to try and present the topic in the most favorable light.  I'd be fine with presenting this article completely from a religious/spiritual perspective, describing it as a belief throughout, but I suspect some want to include the study of mediumship at universities and such.  We can, and probably should include mention of the term being used in a more general sense by the general public.  We may also want to include mention of research into mediumship, but obviously such a section would have to be balanced and include response to and criticism of that research as well.  If the research side stays in the article, I'd recommend putting it in a section separate from the religious discussion instead of mingling the two throughout as it is now.