DONATO. - He was not the initiator, but the leader and principal instigator of the African schism that took its name from him (v. DONATISMO).
The distinction between a D. of Casae Nigrae (Casinensis, Casensis)—the name was extremely common in Africa—and one «of Carthage», both Donatist bishops, is not found in the sources before the conference of Carthage in 411. St. Augustine, not without some hesitation, accepted it (Retract., I, 20 or 21,3), and from then on it became traditional. But the circumstances in which it was proposed, and the fact that one disappears precisely when the other enters the scene, have led various modern scholars to doubt this distinction and reject it, following Chapman; Casae Nigrae, in Numidia, may have been D.’s birthplace.
It is also known that he wrote an epistle in which he maintained that his party alone possessed a valid Baptism; it was refuted by St. Augustine in a lost work, Contra epistulam Donati haeretic. He also wrote a treatise De Spiritu Sancto which St. Jerome (De vir. ill., 93) and St. Augustine (De haer., 69; cf. Epist. 185 or De corrept. Donatist., 1, 1) regarded as Arianizing, or in any case not precisely orthodox with regard to Trinitarian dogma: D. was said to have affirmed «that the Son is less than the Father, and the Holy Spirit less than the Son» («quamvis eiusdem substantiae, minorem tamen Patre Filium et minorem Filio putasse Spiritum Sanctum»).
It is quite probable that D. made some concessions to Arianism, or to the Semi-Arianism of the Eastern bishops, in order somehow to reciprocate the gesture of the conciliabulum of Philippopolis, which had also addressed its synodal letter to D., as bishop of Carthage; but what exactly he thought, and which of the many formulas of faith elaborated around 350 he intended to adhere to, is difficult, if not impossible, to determine now.