Pope Pius IX defined the doctrine of infallibility but it was opposed by many bishops at the council of 1870. Bishop Jose Strossmayer, opposing the infallibility doctrine, told how some popes had opposed other popes, how they had contradicted each other, and how Pope Steven brought former Pope Formosus to trial.
To accent the madness of some popes the story of this trial is worth hearing. Pope Formosus, dead for eight months, was dragged from his tomb and brought to trial by Pope Steven. Before bishops and cardinals the remains of the former pope were brought, dressed in rich apparel, a crown upon his skull and the scepter of the holy office in his hand. Pope Steven questioned the dead man, the former pope; he didn’t answer so was found guilty as charged. The robes were ripped off, the crown taken from his head, and the fingers used in bestowing the potential blessing hacked off and his body dragged through the streets of the city. After the death of Pope Steven, Pope Romanus restored the memory of Pope Formosus. Someone had to be wrong, for these popes directly contradicted each other.
Pope Honorious I was denounced as a heretic by the sixth council in the year 680. Pope Leo confirmed the council’s charges. If popes are infallible how can one condemn another?
Pope Vigilius condemned certain books, later removed his condemnation, later condemned them again, later removed this condemnation, and then condemned them again.
Pope Eugenine sanctioned dueling but Pope Julius II and Pope Pius IV forbade it.
In the eleventh century there were three rival popes at one time. Later Clement III was opposed by Victor III and still later by Urban II. How can popes be infallible when they oppose each other?
The “Great Schism” in 1375 lasted fifty years. Italians elected Urban IV and French Cardinals Clement VII until a council disposed of both and elected another.
Pope Sixtus V had a version of the Bible he declared to be authentic. Two years later Pope Clement VIII declared it to be full of errors. Pope Hadrian II said civil marriages were valid but Pope Pius IV called them invalid.
Pope Eugene IV condemned Joan of Arc to be burned alive as a witch. Later Pope Benedict IV declared her to be a saint. Where is the infallibility?
Some popes are even denied their infallibility—Vigilus, Innocent III, Clement IV, Gregory XI, Hadrian VI and Paul IV all rejected the doctrine of papal infallibility.