The Monk Theodore was called "Sanctified" because he was the first in his monastery ordained to the priesthood.
The Monk Theodore came from Egypt and was the son of rich and illustrious Christian parents. The yearning for monastic life early showed up in him. One time at the house of his parents during the feast of Theophany there was a large party, and the lad did not want to take part in the festivities, grieving that because of earthly joys he would be deprived of joys in the life to come. At 14 years of age he secretly left home and settled in one of the monasteries. Hearing about Pakhomios the Great, he burned with the desire to see the ascetic. The Monk Pakhomios received the arriving lad with love, having been informed by God beforehand about his coming. Remaining at the monastery, the Monk Theodore quickly succeeded in all his monastic tasks, particularly in the full obedience to his guide and in his compassion towards the surrounding brethren. Theodore's mother, learning that he was at the Tabennisa monastery, came to the Monk Pakhomios with a letter from the bishop, imploring a meeting with her son. But the Monk Theodore, fearing to break his vow of renunciation from the world, refused to meet with his mother.
Seeing the strength of mind and ability of Saint Theodore, the Monk Pakhomios once directed him to speak an instruction to the brethren on Holy Scripture. Saint Theodore was then but 20 years old. He unquestioningly obeyed and began to speak, but certain of the older brethren took offence that a newly begun monk should read them a discourse, and they departed. The Monk Pakhomios thereupon said to them: "Ye have given in to the devil and by your conceit your efforts art come to naught. Ye rejected not Theodore, but rather the Word of God, and have deprived yourselves of the Holy Spirit".
Saint Pakhomios appointed the Monk Theodore as overseer of the Tabennisa monastery, and withdrew to a more solitary monastery. Saint Theodore with filial love continued to concern himself over his instructor, and in the final illness of the Monk Pakhomios he looked after him, and when the great abba reposed to the Lord, he closed his eyes. After the death of the Monk Pakhomios, Saint Theodore directed the Tabennisa monastery, and later on he was at the head of all the Thebaid monasteries. The Monk Theodore the Sanctified was famed for holiness of life and a copious gift of wonderworking, and he was well known to Saint Athanasias, Patriarch of Alexandria. Saint Theodore reposed in his old age in the year 368.