About this same time...

…(early fifth century) it happened that Christianity was disseminated in Persia, by reason of the following causes. Frequent embassies were sent to and fro between the sovereigns of Persia and the Roman empire, for which there were continual occasions. Necessity brought it about at that time that the Roman emperor thought proper to send Marutha bishop of Mesopotamia, who has been before mentioned, on a mission to the king of the Persians. The king discovering great piety in the man treated him with great honor, and gave heed to him as one who was indeed beloved of God. This excited the jealousy of the magi, whose influence is considerable over the Persian monarch, for they feared lest he should persuade the king to embrace Christianity. For Marutha had by his prayers cured the king of a violent headache to which he had been long subject, and which the magi had been unable to relieve. The magians therefore had recourse to this deception. As the Persians worship fire, and the king was accustomed to pay his adorations in a certain edifice to the fire which was kept perpetually burning, they concealed a man underneath the sacred hearth, ordering him to make this exclamation at the time of day when the king was accustomed to perform his devotion: `The king should be thrust out because he is guilty of impiety, in imagining a Christian priest to be loved by the Deity.’

When Isdigerdes (Yazdegird I, 399-420/1) — for that was the king’s name — heard these words, he determined to dismiss Marutha, notwithstanding the reverence with which he regarded him. But Marutha being truly a God-loving man, by the earnestness of his prayers, detected the deception of the magi. Going to the king therefore he addressed him thus: `Be not deluded, O king,’ said he, `but when you again enter that edifice and hear the same voice, explore the ground below, and you will discover the fraud. For it is not the fire that speaks, but human contrivance does this.’ The king received the suggestion of Marutha and went as usual to the little house where the ever-burning fire was. When he again heard the same voice, he ordered the hearth to be dug up; whereupon the impostor, who uttered the supposed words of the Deity, was discovered. Becoming indignant at the deception thus attempted the king commanded that the tribe of the magi should be decimated. When this was effected he permitted Marutha to erect churches wherever he wished; and from that time the Christian religion was diffused among the Persians. Then Marutha being recalled went to Constantinople; not long afterwards however, he was again sent as ambassador to the Persian court. Again the magi devised contrivances so as by all possible means to prevent the king from giving him audience. One of their devices was to cause a most disgusting smell where the king was accustomed to go, and then accuse the Christians of being the authors of it. The king however having already had occasion to suspect the magi, very diligently and closely scrutinized the matter; and again the authors of the nuisance were detected. Wherefore he punished several of them, and held Marutha in still higher honor. For the Romans as a nation he had much regard, and prized good feeling on their part very highly. Nay, he almost embraced the Christian faith himself, as Marutha in conjunction with Abdas bishop of Persia gave another experimental proof of its power: for these two by giving themselves to much fasting and prayer, had cast out a demon with which the king’s son was possessed. But the death of Isdigerdes prevented his making an open profession of Christianity. The kingdom then devolved on Vararanes his son, in whose time the treaty between the Romans and Persians was broken as we shall have occasion to narrate a little later.

Socrates Scholasticus, Ecclesiastical History 7.8
St. Marutha, bishop of Tikrit (in Iraq), commemorated 16 February