St. Theodosius was born into a pious family, and began studying religion at a young age. He was a lector while still a young adult, and, drawn to the example of Abraham, left home in order to follow God’s call. In his travels, he met St. Simeon Stylites in Antioch, and was invited to receive blessings and advice.
According to legends, Theodosius then traveled to Jerusalem, where he worked with St. Longinus, who would have been nearly 500 years at that time. He was given the charge of a small church outside of Bethlehem, but he didn’t stay there long.
Theodosius retired to a cave in the desert of Judah, attempting to avoid the vanity that came with the esteem he was receiving from others. He adopted a hermit’s lifestyle, and when news of his holiness began to attract disciples, he built a monastery at Cathismus.
His monastery had to have sections for Greeks, Armenians, and Persians because so many came to join him, but everyone worked together peacefully. Theodosius also built a hospital, a mental hospital, and a hospice near the monastery.
Theodosius opposed the heresies of Eutychianism and Monophysitism, despite large bribes from the Emperor Anastatius.
When Theodosius was older, and in ill health, he developed a medical condition that made his skin dry as stone. He continued to work until he was unable to move, and then spent his last days praying for his community. St. Theodosius died at the age of 105.