The first sign of divine protection (infallibility that cannot be reformed) was that all the Fathers held to a moving sun of Scripture.
The Council of Trent rules: ‘Furthermore, in order to curb imprudent clever persons, the synod decrees that no one who relies on his own judgment in matters of faith and morals, which pertain to the building up of Christian doctrine, and that no one who distorts the Sacred Scripture according to his own opinions, shall dare to interpret the said Sacred Scripture contrary to that sense which is held by holy Mother Church, whose duty it is to judge regarding the true sense and interpretation of the Holy Scriptures, or even contrary to the unanimous consent of the Fathers, even though interpretations of this kind were never intended to be brought to light. Let those who shall oppose this be reported by their ordinaries and be punished with the penalties prescribed by law.’--- (Denzinger – 783/786)
In its catechism Trent states: ‘I Believe in God, Almighty Father, Creator of Heaven and Earth. He followed no external form or model; but contemplating, and as it were imitating, the universal model contained in the divine intelligence, the supreme Architect, with infinite wisdom and power – attributes peculiar to the Divinity – created all things in the beginning. He spoke and they were made… The words heaven and Earth include all things that the heavens and the Earth contain; for besides the heavens, which the Prophet has called the works of His fingers, He also gave to the sun its brilliancy, and to the moon and stars their beauty; and that they may be for signs, and for seasons, and for days and years. He so ordered the celestial bodies in a certain and uniform course that nothing varies more than their continual revolution, while nothing is more fixed than their variety…. The Earth also God commanded to stand in the midst of the world, rooted in its own foundations [Psa. 103:5: You fixed the Earth upon its foundations, not to be moved forever], and made the mountains ascend, and the plains descend into the place that He had founded for them….
Now Trent was a dogmatic Council, and it ruled biblical geocentrism was a divine revelation given in Scripture. In other words the credibility of TRENT itself is inferred by those who state the 1616 decree defending the above teaching was not infallible.
Next confirmation of the infallibility of the 1616 decree was in 1633 when Pope Urban VIII had his Holy Office confirm its infallibility:
The sentence continued: “Invoking, then, the most holy Name of our Lord Jesus Christ, and that of His most glorious Mother Mary ever Virgin, by this our definitive sentence we say, pronounce, judge, and declare, that you, the said Galileo, on account of these things proved against you by docuмentary evidence, and which have been confessed by you as aforesaid, have rendered yourself to this Holy Office vehemently suspected of heresy, that is, of having believed and held a doctrine which is false and contrary to the sacred and divine Scriptures - to wit, that the sun is in the centre of the world, and that it does not move from east to west, and that the Earth moves, and is not the centre of the universe; and that an opinion can be held and defended as probable after it has been declared and defined to be contrary to Holy Scripture.'
The next confirmation of its binding on all Catholics came in 1820:
Fr Olivieri writes: ‘In his “motives” the Most Rev. Anfossi puts forth “the unrevisability of pontifical decrees.” But we have already proved that this is saved: the doctrine in question at the time ...., which is certainly contrary to the Sacred Scriptures, as it was declared.’--- Retrying Galileo, p.213
So, Trent, Pope Urban VIII and Pope Pius VII's Holy Office all confirm the 1616 decree was unrevisable.
THEN CAME THE SO-CALLED PROOFS FOR HELIOCENTRISM, and the removing of all heliocentric books off the Index. Can you even imagine the dilemma this had within the Catholic Church, a dilemma milked by the anti-Catholic world emerging at the time, a conflict that is one of the most written about in the history of both Church and State. The enemies of the Church ridiculed it whereas members of the Church had to try to dismiss the 1616 and 1633 decrees as ‘deciding next to nothing’ as Henry Newman phrased it?
So, where is 'the indefectible Church' as this subject asks? First, you must know that heliocentrism was never proven false. From Einstein's time this non-falsification became public. As the divine protection of the anti-heliocentric decrees of 1616 and 1633 were denied because of the belief that geocentrism was proven false, its infallibility can be restored.
But what about the Church since 1820? Well all they did was remove heliocentric books from the Index. Pope Paul VI closed down the Index altogether but all the heresies in them remained condemned heresies. So too the heliocentric heresy in 1820. But here now is the proof of the Church's Indefectibility. Having searched throughout history I could not find one pope who dared to reform the 1616 decree. There are only two ways in which the law pronounced against Galileoism can be ‘revoked.’ The Church can:
(A) Abrogate it; that is, abolish it completely. But for a law to be abrogated, new legislation must accompany it, stating this clearly, and in justice should state why this is being done. (B) A judgment of a previous pope can be derogated. This means that the legislation still remains in force but it has been modified in some way.
We see then, no abrogation - a modified derogation, yes - had yet been enacted. As far as the ‘theological problem’ was concerned, the 1616 papal judgment of formal heresy still remained in force in 1820.
Which brings us down to the last problem, were those popes and flock who accepted heliocentrism heretics? Well, there is a thing called material heresy. If one accepted heliocentrism convinced it was a proven scientific fact that would be material heresy. All from 1820 thought this was true so no punishable heresy exists.
Which leads to a very important question; does the material heresy of those who are told geocentrism was never proven and that the Church has long defined it as a heresy, actually become guilty of conscious heresy?