He was born in Mogarissos, a village in Cappadocia, Saint Basil’s province. Theodosius’ parents Proheresius and Eulogia were both very pious. Later Eulogia would become a nun taking her son Theodosius as her spiritual father.
When he was younger he felt a desire to imitate Abraham by leaving his parents, friends, relatives and everything else for the love of God. Theodosius set out for Jerusalem at the time of the Holy Fourth Ecumenical Council of Chalcedon held in 451.
When Theodosius reached Antioch, he went to see Saint Symeon the Stylite, to ask for his prayers and blessing. Arriving at the pillar of Saint Symeon he was miraculously greeted by name and was invited to ascend the column. Theodosius climbed the pillar and prostrated himself before Saint Symeon who embraced him with his blessing and prophesied great spiritual glory for Theodosius.
After acquiring monastic life, Theodosius, believing he was unfit to rule over others, fled and took refuge in a cave. He was there for 30 years, praying and fasting.
Many who were attracted to the virtues of the saint became his disciples. Their number was increasing. Seeing that there was no execution, the saint took over their rule. As the number of fellow monks increased, Theodosius built a large monastery and three churches for them. He paid special attention to helping and protecting the poor. In some cases, the monks have fed the poor more than a hundred times. He commanded that this work should not be diminished even in times of famine. The saint miraculously increased the food in situations where the food was not enough. The saint defeated the heresies that appeared at that time. The emperor, angered by this, and exiled the saint.
The saint was afflicted with a very deadly and painful disease in his old age. He never prayed for recovery. He gladly accepted the pain as a solution to his lifelong well-being. A.D. In 529, at the age of 106, the saint ascended to heaven for eternal reward.