Well, I think your results point to the catch in what you're looking for -- do you want religious material in play form, or good theatre that's appropriate for production in a church?  These are very different (though not quite mutually exclusive) questions that will lead to very different pools.

Well, as a huge portion of that category is, frankly, crap by the standards of theatre or literature, maybe try looking in that overlap category -- stuff like Godspell, Cottonpatch Gospel, Fiddler on the Roof, JCS...?

Or do you need non-musical?

"Becket" by Jean Anouilh, "Murder in the Cathedral" by T.S. Eliot, and "A Man for All Seasons" by Robert Bolt are all very good historical plays on religious themes.  There are also religious plays that are not Christian, but might be ok, depending on how tolerant the pastor is (e.g., Sophocles' "Antigone," which really says nothing about religion that the average Christian should find offensive, and says a lot that s/he might affirm).  There are also the medieval morality plays (like "Everyman"), which are not necessarily great theater, but are well-written for what they aim to be.