"Doctrinal Commentary on the Concluding Formula of the Professio Fidei", Congregation for the Doctrine of the Faith
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Some excerpts, in order of weight:
“[All those doctrines of divine and catholic faith which the Church proposes as divinely and formally revealed and, as such, as irreformable] require the assent of theological faith by all members of the faithful. Thus, whoever obstinately places them in doubt or denies them falls under the censure of heresy, as indicated by the respective canons of the Codes of Canon Law.”
Every believer. . .is required to give firm and definitive assent to [all those teachings belonging to the dogmatic or moral area, which are necessary for faithfully keeping and expounding the deposit of faith, even if they have not been proposed by the Magisterium of the Church as formally revealed]. . .Whoever denies these truths would be in a position of rejecting a truth of Catholic doctrine and would therefore no longer be in full communion with the Catholic Church.
[All those teachings on faith and morals - presented as true or at least as sure, even if they have not been defined with a solemn judgment or proposed as definitive by the ordinary and universal Magisterium]. . . require religious submission of will and intellect. A proposition contrary to these doctrines can be qualified as erroneous or, in the case of teachings of the prudential order, as rash or dangerous **
So dissenting against doctrines (depending of the level of teaching) can place one in heresy in the first level, cut oneself off from full communion in the second level, or be erroneous or rash/dangerous in the third level. The Commentary describes these levels of teaching in further detail.
When the Catholic Church receives baptized Christians into full communion, we ask that the Catholic-to-be publically declare, “I believe and profess all that the Holy Catholic Church believes, teaches, and proclaims to be revealed by God.” As
Msgr. William. B. Smith writes, this excludes dissent from “all that the Church believes and all that the Church teaches.”