He was the 19th patriarch of the See of St. Mark (312-326). He succeeded Achillas in the year 312 a.d., just after the end of the great persecution. Alexander faced three problems during his episcopate. He was first troubled over the timing of the Easter observance by a schismatic faction led by a certain Erescentius. Alexander was obliged to write a special treatise on this paschal controversy, referring to previous patristic declarations by Dionysius the Great. This matter remained a sore point until it was settled by the bishops at the Council of Nicaea in 325.

The second problem that faced the occurred at in Upper Egypt, where Bishop Melitius, who had been calumniating Achillas (his predecessor), continued to do the same to Alexander. This culminated in lodging a formal complaint against Alexander before the imperial court under Constantine, but the court paid no great attention to it. More seriously, seems to have established a kind of alliance with the most dangerous of the patriarch’s adversaries, Arius.

Further, consecrated his own schismatic bishops, ignoring his superior. The Melitian schism remained in full force until it was temporarily settled at Nicaea in 325 a.d. through the wisdom of the patriarch, who made a compromise in order to win the bishop back to the fold, thus ending Melitius’ alliance with Arius. The third problem that faced Alexander was the most dangerous of all heretical movements: that of Arius, who was excommunicated by Peter I, only to be readmitted by Achillas and appointed as presbyter of the most ancient of the Alexandrian churches, at Bucalis.

The church was located in the most populous district of the metropolis, where Arius could exercise a great influence on the Christian population. Arius ran as a rival to Alexander at the time of his elevation to the episcopate. Open hostilities between the two broke out when Alexander declared the unity of the Trinity in one of his sermons. Arius at once branded his declaration as mere . Since the Father created the Son of God, he argued, the Son could not be coeternal with his Father. This was the beginning of a long argument, which the future heresiarch enlarged to frightening dimensions as he acquired the support of increasing numbers of followers.

and Works. Alexander I is represented most fully in EusebiusHistoria ecclesiastica. He is also mentioned in the lives and encomiums of his successor, Athanasius the Apostolic. These accounts tend to present Alexander in the shadow of his great successor who, as his secretary, would have led the struggle against Arius and his disciples, both at Alexandria and at the Council of Nicaea, if Alexander had not taken the initiative. Of his works, only one collection of letters related to the controversy was known in antiquity, and of these, only two letters have survived. Also, a homily, De anima et corpore ( and the Body), is ascribed to him in a Syriac version, but the Coptic version attributes this work to Athanasius.

Coptic literature attributes to Alexander an the Alexandrian, known in five codices: VC62.10 (Bohairic, ninth century), VC62.8 (Bohairic, two fragments, ninth century), and three fragmentary codices from the . There is also an elaborated translation to be found in the chapter concerning Alexander in the . It is possible to reconstruct the original redaction of this encomium by comparing the various versions in existence. It must have been composed of three segments, characterized as follows: a literary prologue; the main body, which recounts his birth, life, and martyrdom, with vivid descriptions of the many miracles wrought at his birth, during his life, and after his death; and a literary epilogue.

Except for a few minor variations, the Sahidic and Bohairic redactions are similar, save that the Bohairic version has excluded the martyrdom and posthumous miracles.

The text appears to be a typical, late construction, filled with biblical allusions, vague traditions, and the portrayal of Peter’s Passion. The complexity of the literary structure, the theological competence, and the style make it one of the best examples of of this period, and probably one of the first whose date can be proposed as being at the first half of the seventh century.