Some towns had Donatist and orthodox congregations. This issue caused the Donatist and Novatianist schisms. Optatus then mocks at the recent succession of Donatist antipopes at Rome. In antiquity, the idea led to a schism among the Donatist Christians. Augustine developed his doctrine of the Church principally in reaction to the Donatist sect. His appointment as Bishop lead to the Donatist Controversy of the Late Roman Empire. It became a stronghold of the Donatist heresy until its conquest by Muslim Arabs. Outside Carthage, Donatist churches and clergy were undisturbed. The Donatist schism was a major disruption to the church. Also attracted were the dissendent Donatist Christian churches, and anti-Roman, anti-taxation sentiment. The Donatist schism had a hold in the city around 411. He also combated against the Donatist heresy, popular particularly in North Africa at the time. After Optat, Thamugadai had two bishops Gaudentius (Donatist) and Faustinus (Catholic).