In answering this objection one must first make clear the Churchs
distinction between public and private revelation. The Catholic Church
certainly admits that public revelation ended with the death of the last
Apostle, St. John. Nothing can be added to the Deposit of Faith finally
delivered once and for all by Christ to the Apostles. All Christians without
exception must accept and believe entirely what is contained in public
revelation. What is allowed, however, is a legitimate development of
doctrine, that is, a deeper and greater understanding of truths already
revealed and believed. One finds an example of this in the history of the
doctrines of the Blessed Trinity and the divinity of Christ. It was not until
centuries after the Apostolic age that clear and unequivocal formal solemn
definitions were made by the Church, delineating the precise parameters of
these beliefs. None of these formal pronouncements, however, contradicted
the implicit and explicit statements found in the Scriptures. The same is the
case with regards the Marian dogmas.