Well-Meaning Racism
The silliest thing about the story is the idea that a white European Catholic Christian brought "enlightenment" to the Asian natives. The entire set-up is Asian - Asian culture, Asian religion - the whole place"looks like" a Tibetan setting.
These ancient, mystical cultures have discovered deep spiritual truths, and have produced enough enlightened sages, to need no help from lost Westerners wandering into their countries. Yes, the old priest/guru/lama admitted that the natives told him the secret of long, healthy life, that he never needed to amputate his leg, and yes, here he is at an abnormally advanced age. But so what?
By his own acknowledgement, he proceded to teach the locals his own beliefs (although there is a slight nod to universality when he says he "taught the best" of other beliefs as well - but how in Hell would a Jesuit know suffiently about those other beliefs to teach them?). LH is a social embarrassment - and that goes for the original film and Hilton's novel. Let the Enlightened East be as it is, without meddling from Westerners with an agenda of mass conversion!