CONSTANTINE considered himself a bishop in externals. His Christian successors inherited this title, and acted in accordance with it. One of them, Theodosius II, voiced their mind when he said that "the first duty of the imperial majesty was to protect the true religion, whose worship was intimately connected with the prosperity of human undertakings."[1]
[1] Theodosii II, _Novellæ_, tit. iii. (438).
This concept of the State implied the vigorous prosecution of heresy. We therefore see the Christian emperors severely punishing all those who denied the orthodox faith, or rather their own faith, which they considered, rightly or wrongly, the faith of the Church. From the reign of Valentinian I, and especially from the reign of Theodosius I, the laws against heretics continued to increase with surprising regularity. As many as sixty-eight were enacted in fifty-seven years. They punished every form of heresy, whether it merely differed from the orthodox faith in some minor detail, or whether it resulted in a social upheaval. The penalties differed in severity; i.e., exile, confiscation, the inability to transmit property. There were different degrees of exile; from Rome, from the cities, from the Empire. The legislators seemed to think that some sects would die out completely, if they were limited solely to country places. But the severer penalties, like the death penalty, were reserved for those heretics who were disturbers of the public peace, e.g., the Manicheans and the Donatists. The Manicheans, with their dualistic theories, and their condemnation of marriage and its consequences, were regarded as enemies of the State; a law of 428 treated them as criminals "who had reached the highest degree of rascality."
The Donatists, who in Africa had incited the mob of Circumcelliones to destroy the Catholic churches, had thrown that part of the Empire into the utmost disorder. The State could not regard with indifference such an armed revolution. Several laws were passed, putting the Donatists on a par with the Manicheans, and in one instance both were declared guilty of the terrible crime of treason. But the death penalty was chiefly confined to certain sects of the Manichcans. This law did not affect private opinions (except in the case of the Encratites, the Saccophori, and the Hydroparastatæ), but only those who openly practiced this heretical cult. The State did not claim the right of entering the secret recesses of a man's conscience. This law is all the more worthy of remark, inasmuch as Diocletian had legislated more severely against the Manicheans in his Edict of 287: "We thus decree," he writes Julianus, "against those men, whose doctrines and whose magical arts you have made known to us: the leaders are to be burned with their books, their followers are to be put to death, or sent to the mines." In comparison with such a decree, the legislation of the Christian Emperors was rather moderate.