How much of catholic doctrine can one ignore and still be a catholic?

These days, many catholics remain in the faith because it is cultural. Great grand-ma to today have been catholics, it runs in the family. Many like close ties of mine and friends no longer go to confession. According to their conversation, the Pope is no longer that religious authoritative figure.As long as you show up on Sunday for the celebration of the mass, you are a full fledged catholic. If you do not believe me, consider that a reputed Mafia person may have his burials in a Catholic church. It is a cultural movement. I guess that you can ignore all you want and still be a catholic if you want. We tend more to defend the religion than God's Words.