 The Holy Spirit was included at the First Council of Constantinople (381 CE), where the relationship between the Father, Son and Holy Spirit as one substance ("ousia") and three co-equal persons ("hypostaseis") was formally ratified.Ignatius, second bishop of Antioch, who was martyred in Rome around 110 AD, wrote a series of letters to churches in Asia Minor on his way to be executed in Rome.The conjunction of Father, Son and Holy Spirit appears in his letter to the Magnesian church