Originally Posted by Bede

If you claim the earth is flat and that the fathers and the magistratum of the Catholic Church had misinterpreted their bibles in beleiving it a sphere, you would would be a heretic. The earth as a sphere is unanimously defined by the fathers who express an opinion, which is the very definition of Catholic tradition which is binding on Catholics.

The only reason that we have a definition against heliocentricism is because the matter came up with Galileo. Oddly, while heliocentricism is formally heretical, not being a geocentricist is merely erronous in faith - wrong but not illegal. If someone had said the earth was flat (and was getting attention rather than being treated as a nutter) they would have suffered the same fate as Galileo. You are claiming that theologians were free to claim the earth was flat if they wanted. In fact, they could not have done this.

This all ignores the fact you have already lost the original argument when you claimed wrongly, after Sagan, that "it was popular in certain theological circles during the Middle Ages to assert that the Earth was, in fact, flat". Why not just leave it at that rather than try to find a straw to clutch on?

Bede

Bede's Library - faith and reason

Originally Posted by Saint Thomas Aquinas

As Augustine says (Ep. xliii) and we find it stated in the Decretals (xxiv, qu. 3, can. Dixit Apostolus): "By no means should we accuse of heresy those who, however false and perverse their opinion may be, defend it without obstinate fervor, and seek the truth with careful anxiety, ready to mend their opinion, when they have found the truth," because, to wit, they do not make a choice in contradiction to the doctrine of the Church. Accordingly, certain doctors seem to have differed either in matters the holding of which in this or that way is of no consequence, so far as faith is concerned, or even in matters of faith, which were not as yet defined by the Church; although if anyone were obstinately to deny them after they had been defined by the authority of the universal Church, he would be deemed a heretic. This authority resides chiefly in the Sovereign Pontiff. For we read [Decret. xxiv, qu. 1, can. Quoties]: "Whenever a question of faith is in dispute, I think, that all our brethren and fellow bishops ought to refer the matter to none other than Peter, as being the source of their name and honor, against whose authority neither Jerome nor Augustine nor any of the holy doctors defended their opinion." Hence Jerome says (Exposit. Symbol [Among the supposititious works of St. Jerome]): "This, most blessed Pope, is the faith that we have been taught in the Catholic Church. If anything therein has been incorrectly or carelessly expressed, we beg that it may be set aright by you who hold the faith and see of Peter. If however this, our profession, be approved by the judgment of your apostleship, whoever may blame me, will prove that he himself is ignorant, or malicious, or even not a catholic but a heretic." (Summa Theologica II II, P. 11, Q.2, A.3)

Originally Posted by Steven Carr

Apart from Lactantius ,Christian writers abandoned the Biblical view of a flat-earth with a dome, and turned to the pre-Christian, Hellenistic view of a spherical Earth.

You know, if you look really hard, evidence of Christian borrowing from non-Jewish, pagan cultures can be quite impressive.