Hosius’ date and place of birth are unknown, although we can assume it was in Cordoba since it was the custom then to choose bishops from their own home town. He was one of the most significant figures in the primitive Hispanic church, whose personality shone out throughout the empire.
He was a religious assessor to Emperor Constantine, acted as his deputy in ecclesiastic affairs, and became his right-hand man.
He presided over the Council of Nicea (325 AD) which had been called to counter the heresy of Arianism. He took an active part in drawing up its canons, especially in composing that symbol of the Catholic faith, the Creed, in which the divinity of Christ was defined.
In the Council of Sardica (343 AD), called by Constans and Constantius, sons of Constantine, Hosius once again played a key part, although this time in a more moderating role.
He returned to Cordoba, and lived a quiet life away from the turmoil of the Eastern Church, although he came back onto the political scene in the shady dealings leading to the conviction of his friend St. Athanasius.