Liberius, pope from May 17, 352 to September 24, 366, was the earliest pope who did not become a saint. The successor of Pope Julius I, was consecrated according to the Catalogus Libenianus on May 22. His first recorded act was, after a synod had been held at Rome, to write to emperor Constantius II, then in quarters at Arles (353?354), asking that a council might be called at Aquileia with reference to the affairs of Athanasius of Alexandria; but his messenger Vincentius of Capua was compelled by the emperor at a conciliabulum held in Arles to subscribe against his will a condemnation of the orthodox patriarch of Alexandria.
In 355 Liberius was one of the few who, along with Eusebius of Vercelli, Dionysius of Milan and Lucifer of Cagliari, refused to sign the condemnation of Athanasius, which had anew been imposed at Milan by imperial command upon all the Western bishops; the consequence was his relegation to Beroea in Thrace, Antipope Felix II being consecrated his successor by three "catascopi baud episcopi", as Athanasius called them.
At the end of an exile of more than two years, the emperor recalled him from exile; but, as the Roman see was officially occupied by Antipope Felix, a year passed before Liberius was sent to Rome. It was the emperor's intention that Liberius should govern the Church jointly with Felix, but on the arrival of Liberius, Felix was expelled by the Roman people. Neither Liberius nor Felix took part in the council of Rimini (359).
After the death of the emperor Constantius in 361, Liberius annulled the decrees of that assembly, but, with the concurrence of bishops Athanasius and Hilarius, retained the bishops who had signed and then withdrawn their adherence. In 366 Liberius gave a favourable reception to a deputation of the Eastern episcopate, and admitted into his communion the more moderate of the old Arian party. He died on September 24, 366.
based on an article from a 1911 encyclopedia