Optatus, sometimes anglicized as Optate, was Bishop of Milevis, in Numidia, in the fourth century, remembered for his writings against Donatism.

[3] In his writings on the conflict between Christians and Donatists, Optatus is notably mild among Church Fathers in his views against schism.

Parmenian had enumerated six dotes, or properties, of the church, of which Optatus accepts five, and argues that the first, the cathedra (episcopal chair) belongs to the Christians, and therefore they have all the others.

An incorrect list of popes follows, ending with, "and to Damasus Siricius, who is to-day our colleague, with whom the whole world with us agrees by the communication of commendatory letters in the fellowship of one communion.

Optatus argues, especially in book V, against the doctrine which the Donatists had inherited from Cyprian that baptism by those outside the church cannot be valid, and he anticipates Augustine's argument that the faith of the baptizer does not matter, since it is God who confers the grace.

His statement of the objective efficacy of the sacraments ex opere operato is well known: "Sacramenta per se esse sancta, non per homines" (V, iv).

In rebuking the Donatists as sacrilegious, he says: "What is so profane as to break, scrape, remove the altars of God, on which you yourselves had once offered, on which both the prayers of the people and the members of Christ have been borne, where God Almighty has been invoked, where the Holy Ghost has been asked for and has come down, from which by many has been received the pledge of eternal salvation and the safeguard of faith and the hope of resurrection?

In book VII, Optatus argues that returning Donatists should be accepted into the church for the sake of charity and unity.

3, 5, 6, 7, 9, and 10) claim to be letters written by Constantine and are addressed to various actors involved in the Donatist Schism, including local officials (nos.

[7] The authenticity of some or all documents has been challenged by scholars such as Otto Seeck (1889),[8] Pierre Batiffol (1914),[9] William Hugh Clifford Frend (1952),[10] and Heinz Kraft (1955).

Since the documents mostly involve letters of official correspondence between Emperor Constantine and persons holding authority in Africa and Numidia, or letters written in these provinces and under the supervision of local magistrates, Edwards suggests that "Our archivist [i.e. the compiler of the appendix] would therefore seem to have been an African of the 'Catholic' party, who had access to public records in his own country, but did not hold any commerce with the Donatists or take pains in gathering evidence overseas.