Augustine was strongly moved by the lawlessness of the Donatists. He produced a series of writings against them, the most important of which survive, though some are lost. Amongst these are Seven Books on Baptism, and a lengthened answer, in three books, to Petilian, bishop of Cirta, who was the most eminent theologian amongst them. The first official connection of Augustine with Donatism was his attendance at the Council of Carthage in 393. He was then aged forty years. He had been a priest for two years, and baptised for only six years.
After the Donatist bishop Maximin rebaptised a Catholic deacon, Augustine tried to resolve this conflict by mediation. He sought a resolution without the Catholics appealing to the imperial power of Rome or the Donatists using the rebellious Circumcellions (a group that resorted to physical violence against people and property). Augustine made contact with the Donatists to arrange a conference. All agreed not to bring up the excesses of the bad men on either side, but the large conference Augustine proposed was never held.
As mentioned above, the Donatists held that sacraments received at the hands of unworthy ministers were not valid sacraments at all. Or at least it seems that they held this. Augustine had a long correspondence and controversy with them, and at one point they apparently replied that they did not hold this. To this Augustine replied, "In that case, will you kindly tell me what the controversy is all about, and what you and I have been debating for the last eighteen months, and why your bishops and ours have been against each other for the last one hundred years?"
The controversy dragged on. Part of the dispute was historical (whether Bishop so-and-so, now seventy years dead, had really done what he was accused of doing), and part of it was theological. Against them, Augustine constantly maintained that the holiness of the Church is not derived from the average level of virtue of its individual members, but is derived from the holy nature of its Head, Jesus Christ. Professor James O'Donnell succinctly describes what happened, "Augustine began his anti-Donatist campaign with tact and caution. His first letters to Donatist prelates are polite, and emphasise his faith in their good will. He assumed that reasonable men could settle this controversy peacefully. But he quickly discovered that reason and good manners would get him nowhere. In the late 390s, then, Augustine resigned himself to a course of action others in the church had long been urging: the invocation of government intervention to repress the Donatists."
Augustine was dismayed at the use of military coercion in matters of religion, but consented to the new policy when he became convinced that no other method appeared effective. Even so, 2217 under the leadership of Gildo the Donatist church grew. In the year 397, his stopping the departure of grain ships to Italy forced a confrontation with Rome. When the Emperor feared the ruin of government in his North African territories, his Roman navy attacked the Donatists. They killed Gildo and many Donatist partisans, including their bishop Optatus of Timgad. In the following years, continuing imperial edicts repressed the Donatist sect. The Donatists had been the first to appeal to the Emperor in this struggle to the secular authorities. They then became the first also to declare their entire independence from the imperial power. Augustine himself was in physical danger from Donatists and the Circumcellions. An attempted kidnapping of him failed because his guide took a wrong road. Once returning home from Calama, he was attacked and some of those travelling with him were wounded.
To counter Donatist ideas Augustine wrote his work, On Baptism, in the year 401. With regard to the Donatist idea of the holiness of the church, Augustine drew a fundamental distinction between the present church and the future church, not as two churches but rather as two moments in one and the same church. He said that the pure church was the future church "without spot or wrinkle," and that the present was not the future church. Here on earth the church is holy, but not all its members are holy; it is the Body of Christ, but a mixed body that is composed of both good people and wicked people. It is a field in which the wheat and the weeds grow together until the harvest, visibly united but spiritually distinct. It is a field in which the wicked must be tolerated for the sake of the good. By the year 404, in the letters of Augustine can be seen the development of the struggle. There can be seen the constant stream of converts from Donatism, and the severe measures tempered always by the prayer of Augustine that death be never the punishment of heresy alone. More than once Augustine sought a more gentle treatment for the Donatists. In the year 405 Emperor Honorius applied against the Donatists laws combating heresy. Their property was confiscated, and their clergy were exiled.
There were public floggings, and the invalidation of wills and contracts made by Donatists. The Donatist bishop Petilian complained to Augustine that Catholics carried on a war against them. He also said that the only victories for Donatists was to be killed or to escape. He asked how Augustine could justify this killing because Jesus never killed anyone. Augustine replied by suggesting that Christian love meant ecclesiastical unity. He also advocated the use of force against the Donatists, asking "Why . . . should not the Church use force in compelling her lost sons to return, if the lost sons compelled others to their destruction?" ("The Correction of the Donatists.") Petilian angrily charged that love does not punish people nor inflame emperors to take away the lives or to plunder the possessions of individual citizens. Augustine said that Christ was punishing people when he expelled the merchants from the temple with a whip.
Vincentius was an old friend of Augustine from Carthage who became a Donatist. He was shocked that Augustine supported the use of state power to force Donatists back into the Catholic Church. Augustine quoted the parable of the wedding banquet in Luke 14:16-23 when later guests were compelled to come. Today, this use of Luke 14:16-23 by Augustine would not be considered correct, yet it shows the heat that the Donatist situation caused. The Donatists had used the Circumcellions, who were bands of violent thieves, and the Catholic side had used the force of government, army and navy. Luke 14:16-23 is Jesus' story in which the rich man, whose friends would not attend a marriage feast, instructs his servants to search the roads for strangers, and "compel them to come in". It is clear from the context that the "compulsion" approved by Jesus here would be no more than that required to overcome the natural hesitation of a tramp unexpectedly invited to go immediately to feast with his social superiors.
Mainly in the letter to Donatus, Augustine applied this to a justification of the use of state coercion to suppress the Donatist movement in North Africa. Augustine expressed support for the repression as long as it was accompanied by instruction. He favoured uprooting the Donatist heresy with arguments, but opposed hunting for heretics with spies and agent provocateurs. For over a decade some Donatists in North Africa terrorised the countryside and plundered isolated villages and rich farms. They forced non-Donatist Christian landowners to trade places with their slaves, and enjoyed the sight of the humiliation of the landowners. In 411 AD Augustine was instrumental in having the Roman Emperor Honorius send Marcellinus as an imperial commissioner to North Africa.
He attempted to solve the Donatist problem by demanding a conference at Carthage that was attended by 286 Catholic bishops and 284 Donatist bishops. Marcellinus was a devout man who later became a friend of Augustine. After a week of debate by the opposing bishops Marcellinus officially decided in favour of the Catholics. Soon an imperial edict authorised the confiscation of all Donatist property and the fining of their clergy. Any who persisted as Donatists lost their civil rights, and some were deported. Marcellinus complained to Augustine that Christian teaching contradicted the duties of Roman citizens.He said it especially contradicted the call of Jesus not to resist evil with evil when the empire was being invaded by barbarians. Augustine would eventually answer Marcellinus in his massive and most original book, City of God. In return, Augustine appealed to Marcellinus not to use capital punishment on the Donatists so they would not be considered martyrs by their followers. Augustine here used a political argument rather than a theological one.
Soon after the year 420, the Donatist movement died out. Augustine had triumphed, but at a high cost. He had helped to open the way to the use of civil power to enforce theological orthodoxy. This was a path subsequently revisited by the Inquisition in medieval Europe and by other forces of the Protestant Reformation and Counter-Reformation. The expediency of bolstering theological argument with governmental muscle has never proved satisfactory. AN1208