From Soldier to Monk
The sources present Anastasius's conversion as bound up with the True Cross. As a soldier in the army of Chosroes II, he took part in the Persian campaign that seized Jerusalem in 614 and bore the Cross of Christ back to Persia. Learning that the Lord himself had been crucified upon it, he was drawn to inquire into the Christian faith, which he came to know during the army's stay at Chalcedon.
Leaving military service, he was baptized and given the name Anastasius, a name connected with the resurrection of Christ. The tradition records that he received baptism at Jerusalem and that he then became a monk there, spending about seven years in exact monastic discipline before he was moved toward martyrdom.