He moved as a young man to Constantinople to work as a craftsman. After the Turkish conquest of Constantinople, many Christians had denied Christ and embraced Islam. John spoke with many of these about the Faith and challenged them for their betrayal of Christ. Shamed and angered, some of them had him arrested, falsely stating that he had earlier accepted Islam and then returned to Christianity, which is punishable by death in Islamic law. He was tortured and cast into prison. When he was brought out for more torture on the day of Pascha, John came forward full of joy and singing 'Christ is risen from the dead!' To his torturers he cried, 'Do what you will to me, and send me as quickly as possible from this transient life into life eternal. I am Christ's servant; I follow Christ, and I die for Christ that I may live with Him.' He has bound in chains and taken to be burned, but when he ran joyfully into the fire, his tormentors pulled him from the flames and beheaded him instead, then threw his head and body into the fire. Christians were able to gather a few of his wonderworking relics and bury them in the Great Church in Constantinople.