[Bruno]

That is an easy change to make, for your your campaign - replace the Power Modifier with the Unholy or Holy PM, and change the note on the spells, et Voilla.

I find more references to "secular" elementalists in stock fantasy than religious ones, so I think the default from DF 9 is fine (at least, in psuedo-western games the way DF is). Necromancers seem to be split 50/50 as religious and secular figures so YMMV.