There is little known for the life of Kyriakos, but through the lives of other saints we have learned more of him.
After Kyriakos was ordained a priest, in a department of the Church of Saint Sophia in Constantinople he managed the finances. After Patriarch John the Faster reposed in the year 595, Kyriakos was then made Patriarch of Constantinople.
He remained Patriarch for 11 years, and he worked hard for the church and for the people. He desired to make God’s will.
Although he is called Bishop of Constantinople, at the time he was Bishop, in the year 214, Constantinople was at the time called Byzantium. Since Kyriakos lived on the opposite shore in a region called Argyropolis he was known as Bishop of Agryopolis and Byzantium.
Kyriakos was blessed with Godly insight as well as the gift to do miracles and this is revealed to us in the special case of Saint Kastinos, who is commemorated January 25.
Kastinos suffered from demonic possession, and through God’s grace he learned of Bishop Kyriakos. Seeking his aid, he crossed the shore and immediately Kyriakos healed him of his demonic possession. Kastinos desired to become a part of the faith, so Kyriakos then baptized him as well.
God blessed Bishop Kyriakos with the foreknowledge of Kastinos purpose. Kyriakos was revealed that Kastinos would one day lead a large group of Christians, so Kyriakos prepared him for his future.
He taught Kastinos the history of the church, as well as the duties as a priest. He also explained the duties in a church and the importance of maintaining the rich tradition.
Kastinos was ordained as a Bishop and he would succeed Kyriakos after his repose.
Kyriakos served for another 16 years as Bishop and he guided Kastinos toward merging the Argypolis with Byzantium. God revealed to Kyriakos that this would one day come to pass.
Kyriakos was humble and meek, but he led his flock well and guided them down the proper path. Saint Kyriakos gave his soul peacefully to the Lord in the year 230 AD.
When Bishop Kastinos became Bishop of Byzantium and Agryopolis, he began working on agreements to merge Agyropolis with Byzantium. Within ten years, he accomplished the goal through God’s will, fulfilling the request of his mentor and guide Kyriakos.
Kyriakos reposed in 606 AD with peace, as his life fullfiled the will of God.
His name day prior to the fourth century used to be on the 30th of October. After they began to celebrate him on the 27th.