Originally from Antioch, Cosmas was educated and resided in Jerusalem for a large part of his life, earning his geographic epithet.
He disapproved of Nikephoros' marriage to the ex-wife of the previous Emperor Michael VII Doukas but took no further action than degrading the priest who performed the service.
Cosmas I resigned or was forced out soon after, as Alexios I's mother, Anna Dalassene, disliked Irene's link to the Doukas family and resented this interference.
[5] The most important synodal action taken by Cosmas I was the condemnation, in 1076–1077, of certain heretical views taken by John Italus, a scholar connected to the Doukas family.
[7] The historian John Skylitzes (continuatus) speaks poorly of Cosmas I, suggesting that the emperor selected him for his lack of greatness, writing that after the death of the previous patriarch, Michael I of constantinople "chose another, not from those of the senate, nor from those of the Great Church, nor any other of the Byzantines famed for word and deed, but a certain monk Cosmas I sprung from the Holy City, and honoured by the Emperor [...] although he was without wisdom or taste [...]".