Well, when Harry uses it as "mystical rebar" that's sponsored magic.
That's kind of my point. Sponsored Magic as 'boost' is kind of the edge case, but that's ALL Soulfire seems to do (according to the novels). And while the ability may or may not actually be granted by the Almighty (as opposed to having been simply unlocked) it feeds on the 'soul' for power rather than some sponsor with an agenda. That's why I think its a really bad model for it. Anyway, not gonna get in a debate about, just voice my opinion.