Help on Infallibility

One of the readers writes:

...I maintain that homosexuality is just as natural and inherently good as heterosexuality.

On women's ordination, I am not questioning the wisdom of Our Lord. I am questioning the wisdom of later "leaders."

Not all teaching is infallible, and that's a fact.

Well, let's just do some "fact" checking, shall we...?

The Doctrinal Commentary (by the Congregation for the Doctrine of the Faith) on the Concluding Formula of the Professio Fidei was signed by Joseph Cardinal Ratzinger, Prefect, and by Tarcisio Bertone, S.D.B., Archbishop Emeritus of Vercelli, Secretary, on June 29, 1998. This commentary was issued coincident with the promulgation of "Ad tuendam fidem" by Pope John Paul II, in which he modified the Oriental and Latin codes of canon law.

One of the best examples and explanations of the Profession Fidei and the Doctrinal Commentary that I've seen was put together by EWTN (Colin Donovan, I believe) and posted on its web site here...

Briefly, the Summary of Categories of Belief in Professio fidei list three categories which are re-stated here, minus the examples:

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I. Divinely Revealed
Doctrines contained in the Word of God, written or handed down, and defined with a solemn judgment of the Church as divinely revealed truths by any of the following:

a) the Roman Pontiff speaking ex cathedra
b) the College of Bishops gathered in council
c) infallibly proposed by the ordinary and universal Magisterium

ASSENT REQUIRED:
These doctrines require of all members of the faithful the assent of theological faith, based on the authority of the Word of God (de fide credendi). Whoever obstinately places them in doubt or denies them falls under the censure of heresy, as indicated by the respective canons of the Oriental and Latin Codes of Canon Law.
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II. Definitively Proposed
Doctrines definitively proposed by the Church on faith and morals 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. They can be defined by:

a) the Roman Pontiff speaking ex cathedra
b) the College of Bishops gathered in council
c) taught infallibly by the ordinary and universal Magisterium of the Church as sententia definitive tenenda.

Such doctrines are joined to Divinely Revealed truths by a) historical relationship or b) logical connection. Even though they are not proposed as formally revealed they could, by dogmatic development, one day be declared to be revealed.

ASSENT REQUIRED:
These doctrines require firm and definitive assent based on theological faith in the Holy Spirit's assistance to the Church's Magisterium and on the Catholic doctrine of the infallibility of the Magisterium in these matters.

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.

There is no difference with respect to the full and irrevocable consent which must be given to teachings set forth as I. Divinely Revealed and II. Those Proposed as to be Definitively Held.
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III. Authentic Ordinary Magisterium

Teachings 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, whether of the Pope or of the College of Bishops.

ASSENT REQUIRED:
Religious submission of will and intellect.
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Particular note should be paid to the "Assent Required" of the above categories. No claim is made that we must "understand" before giving our assent. Understanding is not a requirement. Faith precedes understanding, faith seeks understanding...

In the words of St. Augustine, "I believe, in order to understand; and I understand, the better to believe." (CCC 158)

And we should not forget what Faith is:
Faith is the theological virtue by which we believe in God and believe all that he has said and revealed to us, and that Holy Church proposes for our belief, because he is truth itself. (CCC 1814)