"Therefore He was not man, and then became God, but He was God, and then became man, and that to deify us"-St AthanasiusSt Athanasius was the bishop of Alexandria in the 4th century, most prominently known for his role at the Council of Nicaea. He was the hammer of Arianism, which claimed Jesus is distinct from God the Father. He was sent into exile multiple times, and fled for his life on several other occasions. He is responsible for both the Nicene Creed, and the Athanasian Creed. Both are offical Creeds of the Catholic Church (and recognized by the Eastern Orthodox, as well as most Protestants). He is particularly venerated in the Eastern Churches, both Catholic and Orthodox, especially the Coptic Churches. Though not in name, he led the Egyptian Church that would eventually be known as the Coptic Church. St Athanasius is a Doctor of the Church. His feast is on May 2 in the West.
There was a little mention of theosis in religious education today. It's a really neat area of theology and catechetics, that everyone should be aware of. The Wikipedia article does a good job of explaining it, so I'll just send you there. Ignore the LDS crap, and any strange Protestant views, and recognize it for what it is: heresy
It's really a sad reflection on the world that when I typed 'Athanasius' into Chrome, I got a suggestion for 'Euthanasia.'