"How much of this do I have to believe?" This question came in our RCIA group last night as we were discussing the Creed and its role in the profession of faith at the Easter Vigil. The quick answer to the question in the context of our discussion is to say that you must at least be able to say yes to the questions that make up the profession of faith. The longer answer needs to take into account the fact that people coming to the Catholic Church particularly from an evangelical background are likely to have problems with some aspects of Church teaching. So the larger question becomes, can I or should I join a Church if I "have problems" with some aspect of Church teaching, such as the doctrines surrounding Mary?
It seems to me that there are two ways to answer the question. The first way is simple, safe, and orthodox. "Some one hundred years ago a previous Pope named Benedict stated it simply when he said; Such is the nature of Catholicism that it does not admit of more or less, but must be held as a whole or as a whole rejected." So it is not possible to "pick and choose" regarding Catholic beliefs. You accept or reject the entire package of doctrine and magisterial teaching (both ordinary and extra-ordinary). So, if a candidate at the time of initiation did not feel that they could accept all of the teachings of the Church they should not join the Church.
A second, more complicated and slightly risky answer is to recall that adult christians of good will ought to be able to come to their own assent to Church teaching. Of course it is true that some central teachings require my assent. Without believing these things I could not be Catholic . But with these as with other beliefs I ought to be able by prayer and individual study (perhaps with some help and guidance) come to personal assent to the teaching in question. If I cannot come to this assent after prayer and study it might still be that I am called to be a member of the Catholic Church. This would be a matter for personal discernment in consultation with the pastor.
The analogy that we use in RCIA of the people of God on a physical journey (like the Hebrew people of Exodus) provides a way of clarifying these two answers. In the first case the people travel along a single well-worn path. The path is quite narrow and represents the way mapped out by our leaders and the people of God who have gone before us. People generally do not step outside of the boundaries of this path especially because of the danger of losing contact with the group. Outside of the boundaries we recognize that there are other paths that seem to go the way we are going but our path is uniquely ours. In the second case the people of God travel together but sometimes individuals wander a short way from the main path to explore something or another. At certain places where those who have gone before have found danger there is a narrowly marked path and people try to stick to the narrow path at those places. People recognize that those who have wandered a short way from the main path are still part of the group but they also recognize that if people wander too far they will lose contact with the group.
Each of the above answers has advantages and disadvantages. The first answer recognizes the authority of the magisterium. If everyone who is Catholic accepted this answer the Church would "speak with a single voice" and be a stronger moral force in the world. If the whole church practiced this answer it is likely that the Church would be smaller in numbers but perhaps more fervent in belief. The second answer recognizes the importance of the individual in coming to belief. It recognizes that while the magisterium has a central role to play in the faith of believers there is room for a certain diversity of belief within the body of the Church.
So, the answer that, on reflection I would give to my questioning candidate is that the Church is inviting new members to explore the richness of Catholic belief. When the new (potential) believer encounters something that seems difficult for them to believe the invitation is to further explore, study, seek help, and pray. Only the individual candidate together with the pastor or the RCIA director can say if a particular individual should join the Church at any particular time and in any particular circumstance.(now, why couldn't I come up with this when the question was asked?)