The Gospel having spread itself into Persia, the pagan priests, who worshipped the sun, were greatly alarmed, and dreaded the loss of that influence they had hitherto maintained over the people's minds and properties. Hence they thought it expedient to complain to the emperor that the Christians were enemies to the state, and held a treasonable correspondence with the Romans, the great enemies of Persia.
The emperor Sapores, being naturally averse to Christianity, easily believed what was said against the Christians, and gave orders to persecute them in all parts of his empire. On account of this mandate, many eminent persons in the church and state fell martyrs to the ignorance and ferocity of the pagans.
Constantine the Great being informed of the persecutions in Persia, wrote a long letter to the Persian monarch, in which he recounts the vengeance that had fallen on persecutors, and the great success that had attended those who had refrained from persecuting the Christians.
Speaking of his victories over rival emperors of his own time, he said, "I subdued these solely by faith in Christ; for which God was my helper, who gave me victory in battle, and made me triumph over my enemies. He hath likewise so enlarged to me the bounds of the Roman Empire, that it extends from the Western Ocean almost to the uttermost parts of the East: for this domain I neither offered sacrifices to the ancient deities, nor made use of charm or divination; but only offered up prayers to the Almighty God, and followed the cross of Christ. Rejoiced should I be if the throne of Persia found glory also, by embracing the Christians: that so you with me, and they with you, may enjoy all happiness.
In consequence of this appeal, the persecution ended for the time, but it was renewed in later years when another king succeeded to the throne of Persia.