I’m pretty sure he was referencing me since he referenced my quote, though he did confuse me with Jesus. However, it does look like it should be a response to you.
Yes, as I’d stated way above, the rules on teaching once you have the Ability are silent here. Troupes must decide. You go one way, I go the other,
I think the rules are fairly unclear in the reading on whether The Gift allows learning from a non-Magic-Aligned Sup Ability holder. Least the phrasing is not explicit that the teacher must have a magic-aligned ability as well but I believe that is RAI while others think only the end resulting realm-alignment is necessary but freely admit the sentence in English is nebulous as they often are.
EDIT to add: I will also admit I somewhat ignored you and Oneshot's digression into descendants grandchildren. Made my eyes glaze over. felt unrelated.
Two things:
This is a misunderstanding of how having True Faith, Enough Faerie Rank, or a single Infernal Warping point works. If you have any of those you can learn Sup Abilities of the appropriate realm just like you have the gift and Favored Abilities is very important for you. You can start with any of these and no Sup Abilities and learn them in-play OR you can start with one of these and some Sup Abilities and already be a Faerie Doctor, member of a Holy or InfernalTradition OR You can be just a regular Sup Ability having person and only be able to learn via having the virtues (but you still might be associated with a tradition of a particular realm) and not bother having enough faerie rank, True Faith, or a single point of warping from an Infernal source (unlikely to keep that distinction for long).
I think this is an area where troupe discussion, and allowing what feels thematically right for your saga, is the best approach. If you feel a character with True Faith teaching people Divine-related abilities enhances the saga and adds a spiritual dimension to your game, that's good. If you feel it leads to overpowered characters wrecking the saga, then having very firm rules on who can learn what is good.
I suppose the Infernal can always teach abilities to people who will take an Infernal warping point - after all, the Infernal is supposed to be there as the easy shortcut that imperils the souls of the unwary.
Fair enough. Ignore that part of the comments above, then.
@callen, it seems to me that you assume the following: a character with Second Sight can teach it "cross Realm" to someone who already knows it, but not to someone who does not (albeit having the means to learn it "ab initio", e.g. True Faith). This seems very strange to me, and the rules as written for learning new supernatural abilities (p.166 for the Gift, referenced in subsequent books for the True Faith etc.) make no such distinction between the two types of learning - only imposing a penalty and a minimum-xp-gain requirement for the second case.
As for the philosophical justification you bring, first of all, some of the fluff can be read both ways. "Even so every good tree bringeth forth good fruit; but a corrupt tree bringeth forth evil fruit" to me seems to be confirming that an infernalist who learns Second Sight from a divine source learns the infernal version, and viceversa.
As for why a character with True faith could learn Divine Second Sight "ab initio" from an Infernal source, there's a very simple way to justify it. A character with the Gift, True Faith etc. has such a strong association with the appropriate Supernatural Realm, that even supernatural stuff becomes "almost mundane" for the character - learning Second Sight, even ab initio, is not significantly harder than learning Awareness. Of course, that same connection colours the end result, i.e. to what Realm the resulting ability is connected. Cut off that connection (e.g. by removing the Gift, or in a crisis of Faith) and bang, that supernatural stuff obtained through that connection by and large becomes inaccessible.
Also, it seems to me that by an extension of your reasoning, it should be impossible for a character with the Gift to self-initiate Divine Virtues. We know this is not the case.
Then you've really misread what I've written, which is really surprising because you are the one who asked about my personal opinion on stuff separate from what I've said the books specifically say. I've said the rules are silent on the former and are a little too vague to be absolutely sure on the latter. I'm by no means assuming either way on either. I have also stated my personal preferences and why I think they fit the rules well.
This is incorrect. The core rules explicitly make such a distinction:
Once the character knows the Ability, it may be advanced normally. (p.166)
And, no, it isn't only the penalty that changes. The allowable sources also change, and that's a rather important detail when we're considering allowable sources.
Consider asking this question of the potential teacher and student as an SG: As this student with True Faith can learn Divine Supernatural Abilities, does this Infernalist instructor have a Divine Supernatural Ability he could teach to the student? Again, I'm not saying the rules are perfectly clear, but this could be a perfectly valid question based on the rules, right? But if we turn to the rules to have something "advance normally," is there anything about realm requirements ever stated? Meanwhile, is teaching someone an Ability a typical way to corrupt their Ability?
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Don't take my word on it. Instead turn to some of the experts, such as Charles John Ellicott, known as one of the great scholars providing commentary on the bible. He says about this passage:
If there is falseness in the teaching, or in the man, it will sooner or later show itself in his life, and then, even though we judge of the doctrine on other ground, we should cease to feel confidence in the guidance of the teacher.
Yup, he's actually pointing out that this includes corrupt "teaching" leading to evil fruit. Sure, "teaching" here isn't going to refer to teaching Supernatural Abilities described in a game well after his death, but still.
Matthew Henry, another great scholar of the Bible, said about this passage:
Nothing so much prevents men from entering the strait gate, and becoming true followers of Christ, as the carnal, soothing, flattering doctrines of those who oppose the truth.
Yup, he's saying about this passage that the doctrines of the corrupt serve to cut people off from Christ. Not explicitly "teaching," but we again see that it's the instructor's evil.
John Gill, another famous theologian, said about this passage:
if he is a corrupt preacher, or a man of a corrupt mind, destitute of the truth, his preaching will be such as will tend to corrupt both the principles and practices of men
Again not explicitly teaching, but again it's the corrupt preacher that corrupts the listener.
You can see that the way I'm reading that passage is a pretty-well accepted way of reading that passage, though people generally don't apply it within a game. The warning is not for the good to avoid trying to save the evil because preaching to them is useless; that's a total misunderstanding of it. The warning is for the good to avoid being swayed by the teachings of the evil because those teachings endanger the good.
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That's not vaguely an extension of what I've said at all. How does having the Gift prevent having True Faith? How does having the Gift prevent pilgrimages? Etc. I'm sorry, but the path to reach this "extension" is so far from logical reasoning I can't even figure out where you've gone off course, especially since I've been strongly arguing nearly the opposite, that the Gift has no bearing on picking up Supernatural Abilities of other realms, that other realms have their own requirements.