In "The Open Boat," the point of view shifts to the perspective of each man and to an objective, third person narrator. We get the most insight from the correspondent, probably because he is the autobiographical representative of Crane in the story and because he, as a writer, might be the most qualified to describe the fear that all the mean are feeling. (Crane had a similar experience, being shipwrecked off the Florida coast.)
"The Open Boat" is an example of Realism. Realist works tend to give quite harsh, objective accounts of life. In other words, Realist authors present a character realistically with particular attention to the social and natural forces that character must face and possibly overcome. This story is also a Naturalist work. Such texts often involve the struggle of man against nature. By focusing on the realities of this struggle of "men against nature" in the boat, the narrator and the characters spend no time pontificating about religious implications. They spend most of their energy on contemplating survival and potential death.
Although the men are faced with uncontrollable forces, these are the forces of nature. This is a tale about the survival of the fittest and luckiest. That said, one could say that this story is not about religious or spiritual significance; it is about people struggling to survive and how they reckon their own significance in a seemingly indifferent world/nature. The narrator speculates what the men are thinking as they contemplate drowning:
Afterward the man might have had an impulse to shake his fist at the clouds. "Just you drown me, now, and then hear what I call you!"
The man (one of the men in the boat) might scream at the sky, yell at a personified "Fate," in his anger at being faced with death. This might seem like a subtle indication that the men would question God (as sky or the personified Fate) but it is more likely that they are yelling at nature itself. So, again, religion simply has no place here: it is just man versus nature.
It seems like an open and shut case, that religion plays no role in this story and, being a Realist work, religion plays no effectual role in human fate. But, when the men are being rescued in the shallows, someone comes to help them. "He was naked, naked as a tree in winter, but a halo was about his head, and he shone like saint." The religious symbolism here is obvious but it could also be interpreted as a hyperbolic (exaggerated) reaction to being saved.