Gallienus P. Licinius, emperor, son of Valerian, appointed by the senate coadjutor to his father very shortly after Valerian's succession in Aug. 253. In 260 his father's captivity in Persia left him politically irresponsible.
One great act brings him into church history. On his father's fall, he was legally bound to put every clergyman to death wherever found, and to deal in almost as summary a fashion with all other Christians. [See VALERIAN.] Gallienus had had three years' experience of the difficulty and wearisomeness of this task. The "Thirty Tyrants," moreover, were foes formidable enough to attract what little attention could be spared from pleasure. Accordingly, in 261 he issued a public edict, by which Christianity was for the first time put on a clearly legal footing as a religio licita. This edict is the most marked epoch in the history of the church's relation to the state since the rescript of Trajan to Pliny, which had made Christianity distinctly a religio illicita. The words in which Eusebius describes the edict (the text of which is lost) imply no more than that actual persecution was stopped ( H. E. vii. 13), which might have been done without a legal recognition of Christianity; but Eusebius has preserved a copy of the encyclical rescript which the emperor addressed to the Christian bishops of the Egyptian province, which shews that the position of "the bishops" is perfectly recognized by the pagan government. The rescript informs the bishops that orders have been issued to the pagan officials to evacuate the consecrated places; the bishops' copies of the rescript will serve as a warrant against all interference in reoccupying. Thus formally, universally, and deliberately was done what Alexander Severus had done in an isolated case in a freak of generosityâ€” i.e , the right of the Corpus Christianorum to hold property was fully recognized. If Christianity had not been explicitly made a religio licita , this would have been impossible. The great proof, however, of the footing gained by the church through Gallienus's edict lies in the action of his successor Aurelian in the matter of Paul of Samosata. Though Aurelian's bigoted sun-worship and hatred of the church were well known, and his death alone prevented a great rupture, the Catholics were so secure of their legal position as actually to appeal to the emperor in person to decide their dispute; and Aurelian, as the law then stood, not only recognized the right of the church to hold property, but also to decide internal disputes (though they concerned property) according to her own methods.