Apparently the letter led to nothing practical. A new turn was given to matters. A son had beaten his mother, and threatened her life; to avoid Catholic discipline, he joined the Donatists and was rebaptized by them: as Augustin says, he wounded also his spiritual mother by contemning her sacrament. Public registration of the facts were made by Augustin, all the more because the reported instructions, given by bishop Proculeianus to his presbyter Victor concerning the affair, had already been denied. The case presented an opportunity for getting at some rule for the recognition of one another's discipline. Accordingly Augustin addresses himself to Eusebius, a judicious Donatist of higher rank. He professes that his aim is peace; he emphasizes with impatient vehemence his opposition to coercive measures in matters of conscience: neque me id agere ut ad communionem catholicam quisquam cogatur invitus. He asks Eusebius to find out whether Proculeianus had given the order to his presbyter as recorded; whether the bishop would consent to a collation between themselves and ten selected men on each side, agreeably to the original suggestion so that the whole question might be discussed from the Scriptural grounds, not the historical. Some proposals for a meeting either at the Donatist region of Constantina, or at their projected council at Milevis, he could not accept, because both lay outside of his diocese. If Proculeianus objected to the dialectic and rhetorical skill of his counter bishop, the latter would propose Samsucius, bishop of Turris, an earnest but uncultivated man, as a substitute to lead the Catholic side. (Ep. xxxiv.).
Eusebius declined to interfere on the ground that he could not be a judge, so Augustin replies (Ep. xxxv.) that he had only asked him to make some inquiries, because the bishop refused to have any direct communication. The need for some adjustment concerning discipline had become very pressing; a Catholic subdeacon and some nuns under rebuke had been received into full standing by the Donatists, yet their subsequent career had been even more scandalous. Augustin claimed that the Catholics always respected the penal enactments of their opponents. To show his own hostility to compulsory conversions, he cites the case of a daughter, who against the paternal will had joined the Donatists, and had professed among them; when the father was about to use violence for her recall, he was dissuaded by Augustin, and when a presbyter of Proculeianus had shouted abusive epithets at him, although upon the property of a Catholic woman, he neither replied nor allowed others to resent the insult.
A practical treatise is ascribed by some to this time, called de Agone Christiano. In expounding the faith he warns against different groups of heretics and schismatics. In Chap. xxix. 31, he cautions against listening to the Donatist party, who deny the one holy Catholic church to be diffused throughout the whole world, and claim it to be alone in Africa, and there among themselves, against the plain Scripture teaching of its universality; they affirm that the prophecies of its extension have already been fulfilled, after which the whole church perished outside of their remnant. He alludes to the divisions which have befallen them as a retribution for their separation. If the end shall come after the preaching of the gospel to all nations, how can all nations have lapsed from the faith, when there remain some who are yet to hear and believe? This system robs Christ of His glory, and is to be avoided by all who love the Church. (Cp. Retractt. II. iii.).
In 397 A.D., at the death of Valerius, he became sole bishop. In this year, while on a visit to Tibursi, he had met with Glorius and other Donatists, with whom he held a friendly disputation on the origin and history of the schism, during which some Donatist documents were produced which he declared to be false, and from memory recapitulated the archives current on his side. Augustin pursued his journey to Gelizi, where he attended to some episcopal duties, and brought back with him a copy of the Catholic Gesta, and spent a day with these friends in reading them, but could not quite finish. He subsequently reproduces this story with the arguments in a letter. (Ep. xliii.). The chief burden is a criticism of the Acts, highly important in its place, but it must be passed by here save to remark that in speaking of Bishop Secundus, he suggests that it would have been better to appeal to the principalities of Rome or of some other apostolic church, than to have proceeded as he did; he should have preserved the unity at all hazards; had the case been inexplicable, he should have left it to God; if definable, he should have addressed the transmarine bishops, after finding that his peers at home could not adjust the difficulty; disobedience on the part of Cæcilian to such an order, would have made him the author of the schism; but now the Donatist altar is set up against the Universal Church. It may be well to note that throughout the survey of these acts, there appears a manifest contradiction as to the beginning of the appellations. In the next place, the Donatists are held guilty of schism, rebaptism, and resistance to civil correction; of non-communion with those churches concerning whom they read in their lections; and of the demand for purism against the Lord's parable. The angels of the churches in the apocalypse are ecclesiastical powers, not heavenly messengers. The Church cannot be charged with the crimes of the evil men in it. Toleration is the only practice by which unity can be conserved; Moses bore with murmurers, David with Saul, Samuel with the sons of Eli, Christ with Judas. They themselves forbear with Circumcelliones, with Optatus bishop of Thamugada. The emphasis, however, is not so much upon those matters as upon schism. He would rather leave the archives and elucidate the doctrine, in which he claims to have the book of the world; that the Catholics are the Lord's inheritance; that they stand in fellowship with the churches of the New Testament; they are the light of the world. A divine rebuke has befallen Donatism in all the tenets of its particularity, by the schism and return of the Maximianists.
No open door was passed by. On a journey to Cirta, possibly about the beginning of 398 A.D., he visited with clerical friends the aged Donatist, bishop Fortunius, at Tibursi. A great company gathered who interrupted the debate; all attempts at taking notes were finally given up. In a letter (Ep. xliv.) to the Donatists, Eleusius, Glorius, and the two Felixes, who were of the number of those addressed in the previous epistle, he speaks of their witness to the conciliatory disposition of Fortunius, and recounts the substance of the interview, with the desire that it may be submitted to that bishop for correction. The discussion had opened with the question of the Church. Fortunius regretted that Augustin was not in it; the latter reversed the wish. What is the Church? Is it diffused throughout the whole world, or is it confined to Africa? Can the Donatists send letters of communion to any of the apostolic churches? Thence they dissected the Donatist claim to be the people of God, on account of their subjection to persecution; in which it appears that they recorded the schism of the whole world from themselves as the true Church as due to sympathy with the Macarian persecution; up to that time they had held fellowship with the whole world, and as proof thereof brought forward a letter of a council of Sardica addressed to them. From the condemnation of Athanasius and Julius by this document, Augustin, to whom it was new, concluded that this was an Arian council, and was only the more damaging to their theory. The note of persecution being resumed, he maintained that there was no approved suffering unless for a just cause, and hence the justice of the cause must first be established. Though Ambrose had endured violence at the hand of the soldiery, they would deny him to be a Christian, for they would rebaptize even him. Maximianists on the other hand were confessed to be just, although they had been dispossessed of their basilicas by the Primianist appeal to the state. As an offset, Fortunius urged the curious fact that before the election of Majorinus, an interventor had been chosen, whom the Cæcilianists put out of the way. On the following day Augustin had to confess that there was no example in the New Testament to justify compulsion in matters of faith. The next topic was Discipline. Augustin pleaded for toleration in order to keep unity. A point as to Johannic baptism sprang up, but was not pressed. From this time the debate became miscellaneous and repetitious; in its progress Fortunius confessed reluctantly that rebaptism was a fixed practice among them, and that even a Catholic bishop so highly esteemed among the Donatists for his non-persecuting spirit as was Genethlius, would have to submit to the rite before he could be recognized by their body. Augustin proposes a further examination of matters, with a view to peace, but the pacific Fortunius doubts whether many of the so-called Catholics really desire concord, to which Augustin replies that he can find ten men who would heartily enter into such a conference.
On the next day the venerable Donatist calls upon his opponent to resume their talk, until an ordination called Augustin away; we also obtain information of the Coelicolæ professing a new sort of baptism, with whose leader he desired to confer. The letter closes with a proposition to meet in the little village of Titia, near Tibursi, where there was no church, and the population pretty equally divided, and where no crowd could disturb the progress of the investigation; thither all documents should be brought and the whole subject canvassed for as long a time as it might take to terminate the discussion.
During the year Augustin issued a weighty work, which stands closely related to these visits to Fortunius. It was in two books named by himself: Contra partem Donati. Unhappily it is lost, but in the Retractations (II. v.), he says, that in the first book he had opposed the use of the secular power for compelling the schismatics to return to the communion of the State Church, a form of discipline which experience afterwards persuaded him was necessary and wholesome.
Possibly it was at the close of the year 398 that a hint from the Donatist bishop Honoratus was brought by Herotes to Augustin, to the effect that they carry on a correspondence on the questions in dispute between them, and avoid the uproar of public debates. Augustin acquiesces heartily, and at once plunges (Ep. xlix.) into the doctrinal aspect of the matter. He begins with the note of Universality, the Church is diffused through the whole world, to establish which he brings forward some of his key passages, Ps. ii. 7, 8, Matt. xxiv. 14, Rom. i. 5. With all the apostolic churches Catholics communicate, Donatists do not. How then can this universality be limited? Why call the Catholic church Macarian, when the name of Macarius or Donatus is not known in any of these gospel regions? It rests with Donatists to prove how the Church is lost from the whole world and is confined to them. Catholics can rely on the Scriptures only for their theory. Correspondence seems to him also the better plan for discussion. Whether this mutual approach went further is not known.
It may have been in 399 A.D. that the Donatist presbyter Crispinus had met Augustin at Carthage; the two joined words, and both seem to have become heated; the former made promise to resume the parley at a later date, to the fulfillment of which the bishop had occasionally urged him. When Crispinus was elevated to the see of Calama, c. 400 A.D., and was not far from Augustin's diocese, the latter addressed him a letter (Ep. li.) rehearsing these facts. A new rumor credited Crispinus with being ready to enter the arena once more. All salutation is avoided in Augustin's letter, because the Donatists had accused him of servility. For the sake of accuracy and instruction he proposes simply to correspond, whether by one interchange of letters or by many. He pleads that present interests alone may be touched upon. Schism according to the Old Testament was more severely punished than idolatry or the burning of the sacred scroll. The charge of traditorship is set off by the acceptance of the Maximianists, whom the council of Bagai had condemned in such severe terms. If a mistake was made with regard to them why not in Cæcilian's case? If these were really guilty, you consulted the wider duties of unity and toleration, and why not carry these principles farther and apply them to communion with the Catholics? As to the charge of persecution, Augustin will not enter into the merits of the matter theoretically, nor stop to plead the mildness of the measures used, but at once asks why the Donatists used the State to dislodge the Maximianists, and to deny the Catholics the possession of genuine baptism is made foolish by the recognition of the rite as existing among the Maximianists who had been cut off, and were restored without a renewal of the ceremony. The whole world had been condemned by the Donatists without an opportunity of being heard, and yet they accept the sacrament of the condemned Felicianus and Prætextatus. While they deny the validity of the symbol as administered by apostolic communions, and by the missionary churches which brought the light to Africa, they maintain that their little fraction alone is its possessor. Summarizing these arguments as a weight for the bishop to stagger under, he invokes the peace of Christ to conquer his heart.