This article aims at confirming George Christopher Stead's hypothesis that Athanasius, yet a deacon, wrote for his bishop Alexander of Alexandria the encyclical 'Epsilon nu omicron zeta sigma omega mu alpha tau omicron zeta. The demonstration implies, on one hand, a synthesis on the preserved writings of Alexander of Alexandria, and, on the other hand, a reconstruction of the chronology of the documents and events prior to the Council of Nicaea of 325. It leads to an evaluation of Athanasius' christology, at the beginning of his literary carrier, in comparison with his mentor Alexander.