"Donatus... deceived nearly all Africa with his persuasiveness, asserting that the Son was less than the Father, and the Holy Spirit less than the Son." -Isidore, Etymologies 8.51
"For Arius agrees with the Donatists and they with him." -Epiphanius, Panarion, 13.8
For both Isidore of Seville and Epiphanius of Salamis, ancient Christian writers separated both temporally and by the width of the Mediterranean, the Donatist communion was primarily defined as a hazy subset of the "Arian" menace. Such a presupposition was not idiosyncratic: many heresiological texts originating outside North Africa condemn the dissident communion more for its alleged trinitarian heterodoxy than for its refusal to reunite with the hated "Caecilianists."
In North Africa itself, however, such a view was virtually unknown. Augustine will twit his Donatist opponents for their alleged association with the "wrong side" at the 343 Council of Serdica, but he does so under the assumption that such a link would prove deeply embarrassing. Donatist polemicists such as Cresconius and Vincent of Cartenna serenely denounce Arius and his followers, apparently unaware of their own alleged association with the condemned heretic. Donatism as an "Arian" phenomenon is thus an outside imposition almost unattested among its principal combatants.
Where then did such an alternate heresiological tradition come from? In this paper, I will examine this question by carefully assessing those portraits of Donatism we find in heresiological texts originating outside the confines of North Africa in order to determine both the genesis and subsequent evolution of this polemical trope.