Her year of birth is unknown and her death date uncertain, though probably subsequent to 381.
However, she is thought to have played an important role in the church in Nyssa, where she was a deaconess.
This, combined with Nazianzen's statement that Theosebia was buried by the other Gregory in the aforementioned letter, suggest that she was either Gregory of Nyssa's wife or sister, whose funeral he would have been obliged to oversee.
The Cappadocian Gregory of Nazianzus wrote to Gregory of Nyssa about Theosebia, “the pride of the church, the ornament of Christ, the finest of our generation, the free speech of women, Theosebia, the most illustrious among the brethren, outstanding in beauty of soul.
"[9] The St Theosevia Centre for Christian Spirituality is in Oxford, although using an alternate spelling, is named after Theosebia.