Reminds me a bit of my father. My dad has basically said that he doesn't think there is anything after death, and that what you do in life does not matter- so long as you do not 'get caught.' While I cringe at his lack of morals, I do question why he considers himself Catholic. He does not go to church, does not pray, and holds the church in contempt.

I can see that it is not a cultural signifier, so my idea is that he fears creating any problems within the family. Other people in the family might outright ostracize him for openly stating his beliefs without the mandatory "but I'm a Catholic!" added in at the end. Perhaps it is a similar situation? I can't actually say, since I do not know your father. It's simply a stab in the dark.