Pope Julius I

Pope Julius I was the bishop of Rome from 6 February 337 to his death on 12 April 352. He was appealed to by Athanasius when the latter was deposed from his position as patriarch by Arian bishops, Julius then supported Athanasius and condemned his deposition as unjust. He was notable for asserting the authority of the pope over the Arian Eastern bishops, as well as being attributed with the setting of December 25 as the official birthdate of Jesus.

Source: Wikipedia — https://en.wikipedia.org/wiki/Pope_Julius_I