The GM just implied that Renald might want us to work this as a black ops project for him. Not saying this is true, but it is at least a reasonable possibility so maybe you should get off the high horse.
If Mathilde sacrifices the crystal, Ranald may give a thumbs up to further study, but that's Faith. Truth is disregarding what he wants, going behind his back, and stealing from him. You think he's legitimately okay with Mathilde doing what she's doing? Vote Faith.
The GM said in some many words that this may be a case of Ranald not being able to grant permission if told but being more than capable of looking the other way.
It
may be an act of plausible deniability, or it
may be a test of character as I mused on; we don't
know. Boney essentially said that
if Ranald isn't paying attention right now, then
maybe one explanation for that is he is trying to maintain plausible deniability.
Equally he also said an offhand mention of 'You could pick Faith and get a high-five and get told to research away'. Which I then went 'So it could be a test of character?' to, and Boney went "That's not impossible, but really, if someone wants to do the research they should vote to do the research."
Don't mistake "possible plausible answers for hypotheticals" for "this is the truth, definitely."
I'd note that while Silver719 went 'Okay, if we assume this, then maybe the reason is...' and theorized that maybe Ranald is okay with mortals getting a way to get one over Gods...
my reaction to his theories was "Maybe Ranald doesn't want to be blamed for any theft (or whatevers) we might wind up doing against other Gods?" i.e. It's not about Mortals Versus Gods, but about being able to dodge blame. If Mathilde does wind up doing something to piss off another God or hurt them, he wants to be able to duck blame for that.
Though again, this is all hypothetical and theory.
Personally, I think the most likely result of the Faith, now, is "Sacrificing some energy/fuel, and presumably get a boon/blessing/boost/reward of some sort." That is, that seems to be the most straightforward assumption or common sense assumption here. Sacrifice a thing, get a thing in return, right? (Previously, I thought it might be faith-related variant of doing the research, but Boney clarified that a bit. So... I still am basically comparing this to like the Mystic path of the Mystic/Theologian path like from Karag Dum. But I don't know quite what it means or what it might result in.)