When I had to do a paper on the novel in college, I seized on this idea. I posed the question of why Stephen abandoned his Catholicism, and my answer was that he found in art what he had been seeking in religion, namely a way to transcend the temptations of the flesh. Stephen's philosophy is that when examining art, a person should separate his impression of a piece from any physical or emotional reaction it may provoke. Superior art, according to Stephen, is created through a detachment between the artist and his work, whereby the artist's personality "refines itself out of existence, impersonalizes itself."
I traced the development of Stephen's philosophy throughout the novel. As a child and teenager, Stephen reacts to artistic pieces---books, poems, and the like--by letting himself be overcome by them. Conflict arises one day when he wanders into a bad part of town where he has his first sexual encounters. He knows he faces eternal torment for his actions, but at first he feels "a cold lucid indifference." Then his school has him attend a three-day retreat by a priest who gives a harrowing description of what Hell is like. Here is a brief excerpt from the priest's vivid speech:
In earthly prisons the poor captive has at least some liberty of movement, were it only within the four walls of his cell or in the gloomy yard of his prison. Not so in hell. There, by reason of the great number of the damned, the prisoners are heaped together in their awful prison, the walls of which are said to be four thousand miles thick: and the damned are so utterly bound and helpless that, as a blessed saint, Saint Anselm, writes in his book on Similitudes, they are not even able to remove from the eye a worm that gnaws it....For all its raw emotional power, the speech has an important limitation. The priest describes the speech as being about "death, judgment, hell and heaven," but it is almost entirely about Hell, with scarcely a word about what Heaven will be like. Stephen becomes a fervent worshipper, but soon doubts begin to surface, and he wonders if his new devoutness is driven more by fear than by sincere belief. He has trouble finding a more positive basis for his faith.
The horror of this strait and dark prison is increased by its awful stench.... Imagine some foul and putrid corpse that has lain rotting and decomposing in the grave, a jellylike mass of liquid corruption. Imagine such a corpse a prey to flames, devoured by the fire of burning brimstone and giving off dense choking fumes of nauseous loathsome decomposition. And then imagine this sickening stench, multiplied a millionfold and a millionfold again from the millions upon millions of fetid carcasses massed together in the reeking darkness, a huge and rotting human fungus. Imagine all this, and you will have some idea of the horror of the stench of hell.
What he gains most from that period of atonement is considerable practice at inhibiting his physical reactions. He walks with eyes to the ground; avoids eye contact with women; subjects himself to loud noises and unpleasant smells; and refuses to make himself comfortable in bed. By quelling his receptiveness to sensory experience, however, he undermines the very quality that allowed the priest's speech to influence him in the first place. He ultimately leaves his Catholicism behind when he satisfies his need for a chaste vantage point from which to observe life, without the "chill and order" of the priesthood that first attracted him. And he achieves that purpose through his newfound appreciation of art.
When I looked back on my essay later, I noticed a curious irony. Stephen's philosophy of art was almost the polar opposite of mine. Whenever I'm examining a work of fiction, or film, or music, the first question I ask myself is, "What effect did it have on me?" That question leads me to the most sincere and, hence, authentic, answers. Depersonalizing the process only leads to an artificial response, in my view.
In fact, that's exactly how I approached Joyce's novel. I wasn't sure what my paper was going to be about. But the point in the novel that had the most immediate impact on me was the priest's description of Hell. I knew I had to pivot my reaction to that scene into a larger thesis, and that's exactly what I did.
I wonder if my approach to art has something to do with my Jewish background, just as Stephen's has to do with his Catholic background. Judaism emphasizes the idea of a person being transformed through his actions. That's why Jewish thought is relatively weak on theology. Even Torah study is viewed in this light: you're encouraged more or less to lose yourself in it and then see how it affects you.
Then again, I could be totally off about this theory. I'm generalizing based on two limited examples, my own personal philosophy and that of a fictional character (albeit one based on Joyce himself). But I do believe that it is hard for people to escape their initial influences in life.