On the contrary, Jules initially seems far colder and less redeemable than Vincent. The best example of this is when Jules recites a verse from the Bible, "The path of the righteous man is beset on all sides by the inequities of the selfish and the tyranny of evil men. Blessed is he who, in the name of charity and good will, shepherds the weak through the valley of darkness, for he is truly his brother's keeper and the finder of lost children. And I will strike down upon thee with great vengeance and furious anger those who attempt to poison and destroy my brothers. And you will know my name is the Lord when I lay my vengeance upon you!" (Tarantino). This verse is at least partially derived from Ezekiel 25:17. Later in the movie, Jules reveals that he said those words without believing them, pretending that he was the righteous man. That makes the words, which could have such a strong religious meaning and speak to one's duty to one's fellow man, a duty that a hit man such as Jules, clearly is ignoring, become hollow and meaningless.
However, Jules has a spiritual epiphany when he and Vincent remain unharmed after living through a hail of gunfire. While Vincent attributes their survival to luck, Jules is unable to leave it at luck. Moreover, after what he seems to believe is a miraculous intervention in his life, he is in the car when an "innocent" is killed. Though the death is an accident, it would not have occurred but for the fact that Jules was on the wrong path....
Clearly, Jules begins to recognize that he is not the righteous man. If he is not the righteous man bringing vengeance and furious anger upon selfish and evil men, then who is he? Jules makes several attempts to discuss this issue with Vincent, who seems uncomfortable with the spiritual natures of Jules' discussion and attempts to dissuade him from his newly spiritual point-of-view. Despite that, Jules informs Vincent that he is done with being a gangster.
However, Jules' resolve and commitment is tested almost immediately, because he is in the diner when Pumpkin and Honey Bunny attempt a robbery. Vincent, the logical part of the pair, is in the bathroom, which is good, because, perceiving Pumpkin and Honey Bunny as a threat, Vincent almost certainly would have killed them. However, Jules seems to see in the pair a younger version of himself. He has come to the realization that he is not the righteous man, but, instead, reflects on the fact that he was probably the selfish or evil man. Despite this, he tells the robbers that he is trying very hard to be the shepherd. He shepherds them in an odd fashion, helping them commit a crime, even turning over his own properly-labeled wallet. However, he keeps them from getting killed, which, when one looks at the role of an actual shepherd, is more significant than steering them in the correct direction.
References
Tarantino, Quentin (1994). Pulp Fiction: A Screenplay (New York: Hyperion/Miramax).
