One of the common retorts I hear from people who choose not to practice their Catholic faith is this:
I'm a good person. I don't hurt anyone and I go out of my way to help people. What kind of God would punish me for not going to Church? What kind of God sends people to Hell for missing Mass on Sunday?
Anytime I struggle with understanding why people don't believe in or honor God, all I need do is take a walk around the neighborhood. People don't think they should have to step to one side or move in any way to accommodate someone walking towards them. They are so important, no matter who they are and where they're going, that everyone should just get out of their way. How can people who believe themselves to be so self-important ever consider there is Someone greater than they are?
People are full of themselves, leaving no room for God. They don't realize that whatever inherent goodness they do possess comes from Him and that the only worth their works have is from and and in Him.
I saw this today on the site The Catholic Thing. I love the title and can think of many people on my prayer list who are guilty of the Heresy of Good Personism.