Loraine Boettner in his book, Roman Catholicism, on page 248 begins with the following: “It is difficult to say whether a claim such as that of infallibility is more wicked or ridiculous. It certainly is wicked, because it gives to a man one of the attributes of God and usurps the headship of Christ in the church. And it is ridiculous, because the history of the popes reveals many grievous errors, moral and doctrinal, with one often denying what another has affirmed. The claim to infallibility is so fantastic that it is hard to take seriously since the “infallible” church and the “infallible” popes have made so many mistakes. Many of their solemnly worded decrees are contradictory to the Word of God. And much of the prestige and temporal power of the Roman Church was gained through the use of forgeries such as the alleged “gift of Constantine,” or the Isadorian decretals.

Many of the popes have taught heretical doctrines. Some have been grossly immoral, although the theologians say that this does not affect their official powers. Several have been condemned by later popes and church councils, and some have been declared “antipopes,” that is, fraudulently chosen or elected, and later dropped from the official record. Among popes committing serious errors are the following:

Honorius (625-638 A.D.). “The greatest scandal of this nature is Pope Honorius. He specifically taught the Monothelite heresy in two letters to the patriarch of Constantinople [that is, that Christ had only one will, which by implication meant that he denied either His deity or His humanity]. The opinion was condemned by the sixth ecumenical council (680) which condemned and excommunicated Honorius by name. The Roman breviary contained this anathema until the sixteenth century (until the time of Luther, when apparently the Reformers made so much of it that it was quietly dropped)…. Honorius was a heretic according to Roman Catholic standards and was condemned by church councils and popes for 800 years. Such facts are not known to most Protestants as they arise from the technical study of history. They naturally are not publicized by Roman Catholics. But facts they are. And they entirely disprove the papal claims”. (Fundamental Protestant Doctrines, II, p. 13).

Hadrian II (867-872) declared civil marriages to be valid; but Pius VII (1800-1823) condemned them as invalid.

How can one “infallible” pope, Eugene IV (1431-1447), condemn Joan of Arc (1412-1431) to be burned alive as a witch, while another “infallible” pope, Benedict XV, in 1919, declares her to be a saint?

There has been some dispute in the Roman Church concerning which version of the Vulgate should be used. Pope Sixtus V (1585-1590) preferred the old version, personally supervised every sheet of an edition then being published, and prefixed an editorial bull to the first volume excommunicating anyone who in republishing the work should make any alterations in the text. But it turned out that the work contained so many errors that it had to be recalled, and another “infallible” pope published another version, altered in many particulars.

The condemnation of Galileo for his theory that the earth moves around the sun is a special case in point. “Were Popes Paul V (1605-1621) and Urban VIII (1623-1644) infallible when they condemned Galileo for holding a true scientific theory? Did they not declare the Copernican theory was false, heretical, and contrary to the word of God? Did they not torture and imprison Galileo in the dungeons of the Inquisition for not sharing their erroneous views? In their decree prohibiting the book of Copernicus, De Revolutionibus, the congregation of the index, March 5, 1619, denounced the new system of the mobility of the earth and the immobility of the sun as utterly contrary to the Holy Scriptures”. (Ins and Outs of Romanism, p. 28).

Sixtus V (1585-1590) recommended the reading of the Bible, but Pius VII (18001823) and various other popes condemned that practice.

As regards infallibility in the moral sphere, consider these cases. Pope John XI (931-936), was the illegitimate son of Pope Sergius III by a wicked woman named Marozia. The nephew of John XI, who took the name John XII (956-964), was raised to the papacy at the age of 18 through the political intrigue of the Tuscan party which was then dominant in Rome, and proved to be a thoroughly immoral man. His tyrannies and debaucheries were such that, upon complaint of the people of Rome, the emperor Othos tried and deposed him. Some of the sins enumerated in the charge were murder, perjury, sacrilege, adultery, and incest. Yet, he is reckoned as a legitimate pope through whom the unbroken chain of apostolic authority descends from Peter to the pope of the present day supposedly.

Alexander VI (1492-1503) was one of the Borgia popes, from Spain, and had been made a cardinal at the age of 25. He had six illegitimate children, two of whom were born after he became pope. The charge of adultery was brought against him repeatedly. His third son, Caesar Borgia, was made a cardinal and was appointed to command the papal armies. The intrigues and immoralities of his daughter, Lucretia Borgia, brought a full measure of disgrace upon the papal office. The Roman Catholic historian, Ludwig Pastor, in his History of the Popes, grants that he lived the immoral life of the secular princes of his day, both as cardinal and as pope (V, 363; VI, 140); that he obtained the papacy by the rankest simony (V, 385); and that he brought that office into disrepute by his unconcealed nepotism and lack of moral sense (VI, 139). The eloquent reformer, Savonarola, urged his deposition, whereupon Alexander had him condemned as a heretic, hanged, and publicly burned in 1498.

And yet despite these cases of error and many others that could be cited, the “infallibility decree,” which was retroactive and therefore applies to all earlier as well as later popes, officially pronounces all of the popes infallible as teachers of faith and morals. Probably no other element of the papal system causes the Romanists more embarrassment than this doctrine of “papal infallibility”. In the first place it asserts a doctrine that can be easily disproved; and in the second place it serves to focus attention on the utter unreasonableness of the powers claimed by and for the popes. To Protestants the whole ex cathedra business appears, on the one hand, as particularly monstrous and vicious, and on the other, as just a big joke—a joke perpetrated on the Roman Catholic people who are so docile and unthinking and so poorly informed as to believe in and submit to such sophistry.” Loraine Boettner in his book, Roman Catholicism (pp. 248-253)