Coelestius behind at Carthage. Here Coelestius sought ordination as a presbyter. But the Milanese deacon Paulinus stood forward in accusation of him as a heretic, and the matter was brought before a synod under the presidency of Bishop Aurelius. 
Paulinus' charge consisted of seven items,  which asserted that Coelestius taught the following heresies: that Adam was made mortal, and would have died, whether he sinned or did not sin; that the sin of Adam injured himself alone, not the human race; that new-born children are in that state in which Adam was before his sin; that the whole human race does not, on the one hand, die on account of the death or the fall of Adam, nor, on the other, rise again on account of the resurrection of Christ; that infants, even though not baptized, have eternal life; that the law leads to the kingdom of heaven in the same way as the gospel; and that, even before the Lord's coming, there had been men without sin. Only two fragments of the proceedings of the synod in investigating this charge have come down to us;  but it is easy to see that Coelestius was contumacious, and refused to reject any of the propositions charged against him, except the one which had reference to the salvation of infants that die unbaptized, -- the sole one that admitted of sound defence. As touching the transmission of sin, he would only say that it was an open question in the Church, and that he had heard both opinions from Church dignitaries; so that the subject needed investigation, and should not be made the ground for a charge of heresy. The natural result was, that, on refusing to condemn the propositions charged against him, he was himself condemned and excommunicated by the synod. Soon afterwards he sailed to Ephesus, where he obtained the ordination which he sought.
Meanwhile Pelagius was living quietly in Palestine, whither in the summer of 415 a young Spanish presbyter, Paulus Orosius by name, came with letters from Augustin to Jerome, and was invited, near the end of July in that year, to a diocesan synod, presided over by John of Jerusalem. There he was asked about Pelagius and Coelestius, and proceeded to give an account of the condemnation of the latter at the synod of Carthage, and of Augustin's literary refutation of the former. Pelagius was sent for, and the proceedings became an examination into his teachings. The chief matter brought up was his assertion of the possibility of men living sinlessly in this world; but the favour of the bishop towards him, the intemperance of Orosius, and the difficulty of communication between the parties arising from difference of language, combined so to clog proceedings that nothing was done; and the whole matter, as Western in its origin, was referred to the Bishop of Rome for examination and decision. 
Soon afterwards two Gallic bishops, -- Heros of Arles, and Lazarus of Aix, -- who were then in Palestine, lodged a formal accusation against Pelagius with the metropolitan, Eulogius of Cæsarea; and he convened a synod of fourteen bishops which met at Lydda (Diospolis), in December of the same year (415), for the trial of the case. Perhaps no greater ecclesiastical farce was ever enacted than this synod exhibited.  When the time arrived, the accusers were prevented from being present by illness, and Pelagius was confronted only by the written accusation. This was both unskilfully drawn, and was written in Latin which the synod did not understand. It was, therefore, not even consecutively read, and was only head by head rendered into Greek by an interpreter. Pelagius began by reading aloud several letters to himself from various men of reputation in the Episcopate, -- among them a friendly note from Augustin. Thoroughly acquainted with both Latin and Greek, he was enabled skillfully to thread every difficulty, and pass safely through the ordeal. Jerome called this a "miserable synod," and not unjustly: at the same time it is sufficient to vindicate the honesty and earnestness of the bishops' intentions, that even in such circumstances, and despite the more undeveloped opinions of the East on the questions involved, Pelagius escaped condemnation only by a course of most ingenious disingenuousness, and only at the cost both of disowning Coelestius and his teachings, of which he had been the real father, and of leading the synod to believe that he was anathematizing the very doctrines which he was himself proclaiming. There is really no possibility of doubting, as any one will see who reads the proceedings of the synod, that Pelagius obtained his acquittal here either by a "lying condemnation or a tricky interpretation"  of his own teachings; and Augustin is perfectly justified in asserting that the "heresy was not acquitted, but the man who denied the heresy,"  and who would himself have been anathematized had he not anathematized the heresy.
However obtained, the acquittal of Pelagius was yet an accomplished fact. Neither he nor his friends delayed to make the most widely extended use of their good fortune. Pelagius himself was jubilant. Accounts of the synodal proceedings were sent to the West, not altogether free from uncandid alterations; and Pelagius soon put forth a work In Defence of Free-Will, in which he triumphed in his acquittal and "explained his explanations" at the synod. Nor were the champions of the opposite opinion idle. As soon as the news arrived in North Africa, and before the authentic records of the synod had reached that region, the condemnation of Pelagius and Coelestius was re-affirmed in two provincial synods, -- one, consisting of sixty-eight bishops, met at Carthage about midsummer of 416; and the other, consisting of about sixty bishops, met soon afterwards at Mileve (Mila). Thus Palestine and North Africa were arrayed against one another, and it became of great importance to obtain the support of the Patriarchal See of Rome. Both sides made the attempt, but fortune favored the Africans. Each of the North-African synods sent a synodal letter to Innocent I., then Bishop of Rome, engaging his assent to their action: to these, five bishops, Aurelius of Carthage and Augustin among them, added a third "familiar" letter of their own, in which they urged upon Innocent to examine into Pelagius' teaching, and provided him with the material on which he might base a decision. The letters reached Innocent in time for him to take advice of his clergy, and send favorable replies on Jan.27, 417. In these he expressed his agreement with the African decisions, asserted the necessity of inward grace, rejected the Pelagian theory of infant baptism, and declared Pelagius and Coelestius excommunicated until they should return to orthodoxy. In about six weeks more he was dead: but Zosimus, his successor, was scarcely installed in his place before Coelestius appeared at Rome in person to plead his cause; while shortly afterwards letters arrived from Pelagius addressed to Innocent, and by an artful statement of his belief and a recommendation from Praylus, lately become bishop of Jerusalem in John's stead, attempting to enlist Rome in his favour. Zosimus, who appears to have been a Greek and therefore inclined to make little of the merits of this Western controversy, went over to Coelestius at once, upon his profession of willingness to anathematize all doctrines which the pontifical see had condemned or should condemn; and wrote a sharp and arrogant letter to Africa, proclaiming Coelestius "catholic," and requiring the Africans to appear within two months at Rome to prosecute their charges, or else to abandon them. On the arrival of Pelagius' papers, this letter was followed by another (September, 417), in which Zosimus, with the approbation of the clergy, declared both Pelagius and Coelestius to be orthodox, and severely rebuked the Africans for their hasty judgment. It is difficult to understand Zosimus' action in this matter: neither of the confessions presented by the accused teachers ought to have deceived him, and if he was seizing the occasion to magnify the Roman see, his mistake was dreadful. Late in 417, or early in 418, the African bishops assembled at Carthage, in number more than two hundred, and replied to Zosimus that they had decided that the sentence pronounced against Pelagius and Coelestius should remain in force until they should unequivocally acknowledge that "we are aided by the grace of God, through Christ, not only to know, but to do what is right, in each single act, so that without grace we are unable to have, think, speak, or do anything pertaining to piety." This firmness made Zosimus waver. He answered swellingly but timidly, declaring that he had maturely examined the matter, but it had not been his intention finally to acquit Coelestius; and now he had left all things in the condition in which they were before, but he claimed the right of final judgment to himself. Matters were hastening to a conclusion, however, that would leave him no opportunity to escape from the mortification of an entire change of front. This letter was written on the 21st of March, 418; it was received in Africa on the 29th of April; and on the very next day an imperial decree was issued from Ravenna ordering Pelagius and Coelestius to be banished from Rome, with all who held their opinions; while on the next day, May 1, a plenary council of about two hundred bishops met at Carthage, and in nine canons condemned all the essential features of Pelagianism. Whether this simultaneous action was the result of skillful arrangement, can only be conjectured: its effect was in any case necessarily crushing. There could be no appeal from the civil decision, and it played directly into the hands of the African definition of the faith. The synod's nine canons part naturally into three triads.  The first of these deals with the relation of mankind to original sin, and anathematizes in turn those who assert that physical death is a necessity of nature, and not a result of Adam's sin; those who assert that new-born children derive nothing of original sin from Adam to be expiated by the laver of regeneration; and those who assert a distinction between the kingdom of heaven and eternal life, for entrance into the former of which alone baptism is necessary. The second triad deals with the nature of grace, and anathematizes those who assert that grace brings only remission of past sins, not aid in avoiding future ones; those who assert that grace aids us not to sin, only by teaching us what is sinful, not by enabling us to will and do what we know to be right; and those who assert that grace only enables us to do more easily what we should without it still be able to do. The third triad deals with the universal sinfulness of the race, and anathematizes those who assert that the apostles' (1 John i.8) confession of sin is due only to their humility; those who say that "Forgive us our trespasses" in the Lord's Prayer, is pronounced by the saints, not for themselves, but for the sinners in their company; and those who say that the saints use these words of themselves only out of humility and not truly. Here we see a careful traversing of the whole ground of the controversy, with a conscious reference to the three chief contentions of the Pelagian teachers. 
The appeal to the civil power, by whomsoever made, was, of course, indefensible, although it accorded with the opinions of the day, and was entirely approved by Augustin. But it was the ruin of the Pelagian cause. Zosimus found himself forced either to go into banishment with his wards, or to desert their cause. He appears never to have had any personal convictions on the dogmatic points involved in the controversy, and so, all the more readily, yielded to the necessity of the moment. He cited Coelestius to appear before a council for a new examination; but that heresiarch consulted prudence, and withdrew from the city. Zosimus, possibly in the effort to appear a leader in the cause he had opposed, not only condemned and excommunicated the men whom less than six months before he had pronounced "orthodox" after a mature consideration of the matters involved,' but, in obedience to the imperial decree, issued a stringent paper which condemned Pelagius and the Pelagians, and affirmed the African doctrines as to corruption of nature, true grace, and the necessity of baptism. To this he required subscription from all bishops as a test of orthodoxy. Eighteen Italian bishops refused their signature, with Julian of Eclanum, henceforth to be the champion of the Pelagian party, at their head, and were therefore deposed, although several of them afterwards recanted, and were restored. In Julian, the heresy obtained an advocate, who, if aught could have been done for its re-instatement, would surely have proved successful. He was the boldest, the strongest, at once the most acute and the most weighty, of all the disputants of his party. But the ecclesiastical standing of this heresy was already determined. The policy of Zosimus' test act was imposed by imperial authority on North Africa in 419. The exiled bishops were driven from Constantinople by Atticus in 424; and they are said to have been condemned at a Cilician synod in 423, and at an Antiochian one in 424. Thus the East itself was preparing for the final act in the drama. The exiled bishops were with Nestorius at Constantinople in 429; and that patriarch unsuccessfully interceded for them with Coelestine, then Bishop of Rome. The conjunction was ominous. And at the ecumenical synod at Ephesus in 431, we again find the "Coelestians" side by side with Nestorius, sharers in his condemnation.
But Pelagianism did not so die as not to leave a legacy behind it. "Remainders of Pelagianism"  soon showed themselves in Southern Gaul, where a body of monastic leaders attempted to find a middle ground on which they could stand, by allowing the Augustinian doctrine of assisting grace, but retaining the Pelagian conception of our self-determination to good. We first hear of them in 428, through letters from two laymen, Prosper and Hilary, to Augustin, as men who accepted original sin and the necessity of grace, but asserted that men began their turning to God, and God helped their beginning. They taught  that all men are sinners, and that they derive their sin from Adam; that they can by no means save themselves, but need God's assisting grace; and that this grace is gratuitous in the sense that men cannot really deserve it, and yet that it is not irresistible, nor given always without the occasion of its gift having been determined by men's attitude towards God; so that, though not given on account of the merits of men, it is given according to those merits, actual or foreseen. The leader of this new movement was John Cassian, a pupil of Chrysostom (to whom he attributed all that was good in his life and will), and the fountain-head of Gallic monasticism; and its chief champion at a somewhat later day was Faustus of Rhegium (Riez).
The Augustinian opposition was at first led by the vigorous controversialist, Prosper of Aquitaine, and, in the next century, by the wise, moderate, and good Cæsarius of Arles, who brought the contest to a conclusion in the victory of a softened Augustinianism. Already in 431 a letter was obtained from Pope Coelestine, designed to close the controversy in favor of Augustinianism, and in 496 Pope Gelasius condemned the writings of Faustus in the first index of forbidden books; while, near the end of the first quarter of the sixth century, Pope Hormisdas was appealed to for a renewed condemnation. The end was now in sight. The famous second Synod of Orange met under the presidency of Cæsarius at that ancient town on the 3d of July, 529, and drew up a series of moderate articles which received the ratification of Boniface II. in the following year. In these articles there is affirmed an anxiously guarded Augustinianism, a somewhat weakened Augustinianism, but yet a distinctive Augustinianism; and, so far as a formal condemnation could reach, semi-Pelagianism was suppressed by them in the whole Western Church. But councils and popes can only decree; and Cassian and Vincent and Faustus, despite Cæsarius and Boniface and Gregory, retained an influence among their countrymen which never died away.
 On Original Sin, 13.  Early in 412, or, less probably, according to the Ballerini and Hefele 411.  See On Original Sin, 2, 3, 12; On the Proceedings of Pelagius, 23. They are also given by Marius Mercator (Migne, xlviii. 69, 70), and the fifth item (on the salvation of unbaptized infants) omitted,--though apparently by an error.  Preserved by Augustin, On Original Sin, 3, 4.  An account of this synod is given by Orosius himself in his Apology for the Freedom of the Will.  A full account and criticism of the proceedings are given by Augustin in his On the Proceedings of Pelagius.  On Original Sin, 13, at the end.  Augustin's Sermons (Migne, v. 1511).  Compare Canon Bright's Introduction in his Select Anti-Pelagian Treatises, p. xli.  See above, p. xv., and the passages in Augustin cited in note 3.  Prosper's phrase.  Augustin gives their teaching carefully in his On the Predestination of the Saints, 2.
 Early in 412, or, less probably, according to the Ballerini and Hefele 411.
 See On Original Sin, 2, 3, 12; On the Proceedings of Pelagius, 23. They are also given by Marius Mercator (Migne, xlviii. 69, 70), and the fifth item (on the salvation of unbaptized infants) omitted,--though apparently by an error.
 Preserved by Augustin, On Original Sin, 3, 4.
 An account of this synod is given by Orosius himself in his Apology for the Freedom of the Will.
 A full account and criticism of the proceedings are given by Augustin in his On the Proceedings of Pelagius.
 On Original Sin, 13, at the end.
 Augustin's Sermons (Migne, v. 1511).
 Compare Canon Bright's Introduction in his Select Anti-Pelagian Treatises, p. xli.
 See above, p. xv., and the passages in Augustin cited in note 3.
 Prosper's phrase.
 Augustin gives their teaching carefully in his On the Predestination of the Saints, 2.