The difference here is that the target area for your consideration, the place to develop an exploratory/argumentative stance, is on how these three writers can help illuminate issues of what we could call the post-Christian or (post-Christendom) condition. Even though a tremenous number of people might still consider themselves religious, society/culture as a whole now looks with some skepticism at both traditional religions and, depending on the level of skepticism, even more personalized spirituality.
So, this would be a paper on the rhetoric of, or the literary strategies for, non-traditional spirituality/religion in a skeptical age.
These three works of literature approach in various ways how one may be religious in a skeptical world although for these authors it may no longer be possible to adhere to a formal, historical religion, like Protestant or Catholic Christianity. Come up with a thesis about these three works that exemplify a kind of post-Christian recognition how the authors feel a need to maintain some kind of connection to the realm of the transcendent.