Why are there so many Catholics that know nothing about the Bible or the teachings of the Church
There could be many reasons. Many Catholics know a lot more about the bible than might be evident using only an ability to quote chapter and verse from scripture. One does not have to know what book and verse contains the parable of the Prodigal Son or the Good Samaritan in order to “know” what are the lessons taught from them.
In the last several decades, the strength of catechesis has taken a downturn, I’d go so far as to say that is a predominant viewpoint. The reasons for it are many, and you often hear it blamed on Vatican II or its reforms, but the truth is there is a big disconnect from what Vatican II desired and what resulted. In general, because of so many people trying to make changes, many of them were wrongly directed and went on for some time before their errors or the effect of their error was really felt. There is a generation, maybe two, that did not get the same kind of “old school” teachings that were acceptable for hundreds of years.
There is an element of personal responsibility to this that can’t be ignored. With the resources available today, it’s a pretty dead argument for someone to claim they are ignorant and it’s all the fault of some bad CCD teacher or director. If they aren’t getting the information they need, go online or to a diocesan library and find it. As some previous posters have pointed out, some simply don’t care to do this, they operate on barely minimal knowledge and are satisfied having a paper-thin faith. The first time they encounter someone quoting chapter and verse knocking on their door, they hide because they have nothing to counter it with, and that is truly sad, but it is themselves who put them in that situation. It reflects how important their spiritual life is to them.
Thing is, every church has them, not just the Catholic Church. I know people from just about every major faith you can name that will stumble for an answer if you ask them the simplest question about their faith. I think it’s just because they go to that church because mom, dad, grandma and grandpa went there, not that is is the one among many they would pick because they think it is true.
So the reasons are many.