I also would say that in my opinion a Saint would be using Creation based magic (not corrupted by dark magic). In other words I don't think a wizard who's devout to the old gods, or a dark god could be a Saint.
Especially with this new definition of Saint from Jim, I really dont think a Saint is going to be at all
restricted to Heaven, Creation, or any of the Abramhic themes. Those will be present and well represented, granted, but they would not be restricted to the Christian world; there will be eastern ones too, and african shaman, and probably a variety of them in South America (pre-changes) where Faith is a more critical survival tool.
I'd be willing to bet money that whatever old tibetan priest-monk is in charge of the place Mouse came from could easily be a Saint, for example.
On a darker side, a true Believer in the historic worship of Odin is not going to be a nice person by modern standards, and almost certainly will have more destructive capabilities than creative ones (though they might be an decent poet).
And that's just things that we'd still call the "Good Side", but there are literal "Dark Gods" locked up in Demonreach and they all presumably had worshipers once upon a time, some of which likely also had magic and no other school of thought to provide them with the Control they need.