I have not got clarity on **what, for a convert, constitutes the core of belief for the Catholic Church ** - that is, what will make me a ‘Catholic’. In my studies I have found the following, with regard to the (absolutely vast) Teachings of the Church:
(2) Status: We have got various Church instructions with various degrees of importance – that is, the Vulgate, Old Testament as interpreted, New Testament as interpreted, Sacred Tradition, Catechism, Policy Statements, Vatican Decrees (Papal Bulls, Encyclicals, Pastoral Letters etc), Doctrine/Dogma, Canon Law, Councils (Niceae, Trent, Vatican I and II), Creeds, Liturgy, Beliefs, Old Covenant, New Covenant, Law of Moses, Beatitudes, Various Extraneous Manuscripts, Exemplars from the Life of Christ/Disciples/ Apostles/Saints and others, Theological Scholarship and Biblical Research, Constitutions, Decrees of Church Fathers, Reports of Vatican Commissions inter alia.
Some issues stand out in our contemporary era, and we pay a lot of attention to them in 2007. Dictats and interpretations made at various times (above) will speak to them and help us to obey.
But there are other standard beliefs (transubstantiation, baptism, confession). There are other issues that are less obvious; and it is possible that an individual Catholic might not know there is a belief he or she should know as a Catholic.
How does a Catholic know what to know? What takes priority in terms of knowing? By which interpretations/instructions are Catholics bound? It is clearly impossible for any one layperson to know the entirety of the faith, of Catholic dogma, of what is sin and what is error. Is Catholicism ultimately therefore an individual set of beliefs/doctrines picked up (perhaps rather randomly?) by the individual Catholic? (This is not meant to be provocative: it is a question.)
Ultimately I suppose, this comes down to how Catholicism differs from mainline protestantism, except in the wonderful sense that the Catholic Church has archived and disseminated the beliefs of the Christian Faith down through the centuries. This is of course not true of any other denomination.
(2) Extent of Application: To whom does the Church believe its Teachings apply? (Catholic Christians? All Christians? All faiths? Humanity?)