In about 319, when Athanasius was a deacon, a presbyter named Arius began teaching that there was a time before God the Father begat Jesus Christ when the latter did not exist. Athanasius responded that the Father's begetting of the Son, or uttering of the Word, was an eternal relationship between them, not an event that took place within time. Thus began Catholic Christianity's fight against the heresy of Arianism. Athanasius fought consistently against Arianism all his life. In 328, he succeeded Alexander as bishop of Alexandria. As a result of rises and falls in Arianism's influence, he was banished from Alexandria only to be later restored on at least five separate occasions, perhaps as many as seven. This gave rise to the expression "Athanasius contra mundo" or "Athanasius against the world".
Athanasius is also the first person to identify the same 27 books of the New Testament that are in use today; up until his Easter letter, various similar lists were in use. However, his list was the one that was eventually ratified by a series of synods and came to be universally recognized as the New Testament canon.
See also: Theodelinda