I’ve been engaged in a discussion with someone who claims that Pope Liberius’s actions described below constitute a refutation of what Catholics believe to be the Pope’s charism of infallibility given to Peter by Jesus in Matthew 16:13-19.
Pope Liberius refused to sign the condemnation of Saint Athanasius, so Emperor Constantius tried, unsuccessfully, to bribe Pope Liberius. Emperor Constantius then exiled Pope Liberius and named the antipope, Felix II.
Weakened by two years of exile and wishing to return to Rome, Pope Liberius withdrew his support of the Nicaean dogma on the Divinity of Christ by agreeing to an Arian formula that declared the Son is “like” the Father. Then, Pope Liberius proceeded to condemn and excommunicate Saint Athanasius. These actions were considered heresy by many. Once Pope Liberius submitted, Emperor Constantius recalled Pope Liberius from exile, and the antipope, Felix II, was expelled by the Romans.
Any help would be greatly appreciated.