Holden makes several comments in the novel on Catholicism and Christianity. I'd say his view on religion in terms of its typical followers is rather jaded. He mentions in one of the earlier chapters that he lives in the Ossenburger wing of the school and then proceeds to criticize Ossenburger for thinking of Jesus as a "buddy" from whom a person can pray for material blessings. Then in Chapter 7, we are introduced to Ackley who wants to ignore Holden's suffering because he has to go to mass in the morning. Hence, the Christians that he runs into are only Christians by name and not by action. Religion then because another phony mask that people wear to hide their flaws.
At the same time, Christianity as an institution that exists parallel to the world of adulthood, and yet remains outside of it, is something that naturally appeals to holden. He definitely seperates the spirit of religion from the mask of religion that phony people put on to make themselves look good.
Note in chapter 7 how Holden asks Ackley whether or not he has to become a Catholic in order to become a monk. Also note the reverence that he has for the two nuns.
The scene with the two nuns is particularly insightful as to how Holden views himself within the context of relgion. He views himself is dirty and the nuns as pure. This can be seen with his discomfort at having to discuss Romeo and Juliet because the story line involves sex. Toward the end of this chapter, he accidentally blows smoke into the nuns faces and "apologizes" like a "madman". In conjunction with the breath motif, which symbolizes how Holden views himself as empty of the holy spirit, and the 'madman' motif, which alludes to the 'lunatic' in the bible who was healed when Christ breathed upon him to exorcise his demons, it is clear that the last lines of the chapter with the nuns indicates how Holden views himself as dirty, stained, and the nuns as holy, innocent and pure.
Conclusion: I think Holden puts religious values and Christianity upon a pedestal because it is so far outside the ugliness of society. When he does see people use religion as a pretext for paradoxically non-christian actions, he condemns the people, not the religion. His sarcasm would not be sarcasm if the paradox did not exist between Christ-like claims and un-Christ like behavior. The paradox would not exist if he completely condemned Christianity in the same way that he condemned most all adults. (The nuns are an exception since they are viewed as being entirely affiliated with the church and therefore, not 'of this world'.)