Keep in mind that nothing about the definition of Saint that we've been given indicates it would be specific to TWG or the Angel team. It /could/ I guess, though that Team has a lot of rules about intervention so it'd be trickier than the more 'pagan' options. I doubt Soulfire plays a role that often, given that it took a major breach by Satan himself to allow for it. I think the real critical thing is that it's a blending of normal magic and Faith Magic, maybe even /Sponsored Magic/ to use the rpg term.