The saint was a priest and a teacher of Christians. He built a house of prayer (i.e. a small church) where he used to gather hosts of Christians and teach them to venerate Christ alone as the only true God and know no other God but Him. For the sake of his parishoners, he hid when accused to the governor. But the Lord appeared to him and told him: "Go, Karterios, and show yourself to those asking for you. I shall be with you because you will suffer much for My name, and through your example many people will believe and be saved." Then the saint was filled with joy; he thanked God and presented himself to the authorities.
First Karterios was put in prison. Then, when he appeared in front of the governor, he was ordered to sacrifice to the false god Sarapis. But through the saint's prayer the idol was thrown to the ground. Next Karterios was whipped by sixteen soldiers. Then they hung him from a stake and pulled off the nails of his hands and feet with razors. But, although they tore his whole body with nails, he withstood all these torments with the help of a holy angel and was restored to health. However, the governor ordered his men again to pierce the martyr's ankles with an iron rod and to put a ploughshare on his holy chest. Then they ordered him to sit on a hot iron stool and finally they flung him into prison.
When it was dark, the Lord appeared to him again and unbound his chains. Then he restored his health and took him out of the prison's doors. Thus many of the unfaithful, seeing him healthy, rushed to be baptised by him and were freed from their diseases. Because of this the saint was punished again. Once more they hung large stones from his hands and feet. They whipped him on his belly and burnt him with lighted candles while they were thowing sulphur and tar on him. Then they dripped boiled lead in his mouth. Finally, they put him into the fire, but he remained unharmed and continued singing hymns and thanking God. A Jew who was standing by became enraged. This villain procured a spear with which he stabbed the saint, piercing his side. At first so much water came out of his side that the fire of the furnace was put out, and then his blood was shed as well. In this way this courageous fighter commended his soul to the hands of God and received the crown of martyrdom from Him.