I think that a lot of “Catholics” find themselves in the same boat as your father. I personally believe that one cannot be A if one doesn’t meet the criteria for A–that goes for anything in life.
“I’m a Catholic, but I want universal abortion rights.” Nope
“I’m a Catholic, but the Church should change its teachings on homosexuality.” Nope
“I’m a Catholic, but I really don’t believe that stuff.” Nope
You can be one clause or the other. Your dad is probably a great guy, and he probably understands as well as he’s been taught (that goes for all of us), but I don’t believe he can be a Catholic without accepting the Bible, Catechism, Magisterium, etc.
Thoughts?