On the question of Christianity and esoterism, you are right that this was the central point of division between Guénon and Schuon. The former claimed that the Christian sacraments, originally instituted by Christ as fully initiatic rites, had been “lowered” to a purely exoteric level by the authorities of the church in the early centuries and that other, esoteric rites were then added for those few able to follow a gnostic path. Schuon very forcefully repudiated this idea. You can read his arguments in this regard in René Guénon: Some Observations (Sophia Perennis, 2004).

You spoke of being “surprised” that such “giants” as RG and FS would disagree over so fundamental a point. But frankly your surprise is a little surprising to me, if I may be candid. It is important for anyone aspiring to a jnanic Path that he learn to distinguish at the very outset between the Path as such—including both doctrine and method—and the human dimensions of those who teach it.

If you think about this carefully, you will see that the dispute in question, far from being the exception, is nearly a rule in spiritual communities, to say nothing of “schools of thought”; we see this not only among gurus, startsi, and shaykhs, but even among the disciples and companions of avataras and prophets in the earliest days of a new Revelation.

Consider—as but one example out of many that could be mentioned—the single verse of scripture, Galatians 2:11, where Saint Paul writes about his confrontation with Saint Peter: “When Peter was come to Antioch, I withstood him to the face, because he was to be blamed.” What if you had been an aspirant to the Christian community at this point and had chanced to be present when these two large personalities (to say the least) came into collision? If your criterion or expectation was that a true Path would include no such lack of “harmony” among its followers, then you would have doubtless gone your way disappointed—obviously to your own disadvantage.