Born in Aquila, Italy, Saint Pius I succeeded Saint Hygenus in AD 140. Church tradition testifies that he was the brother of Hermes, the author of the ancient book The Shepherd of Hermes.

Church scholars believe that Saint Pius I would also have been a salve just like Hermes. He would have been later freed from slavery.

Although the first centuries were marked by religious persecution, the reign of Pope Pius I was generally a period of peace in the Church. He was therefor able to lead the church to deep faith. However, he had a great responsibility to protect the truths of the faith and the believers from false teachings and heresies.

Like Saint Hygenus, Pope Pius I strongly opposed the teachings of Cerdo and Valentinus, propagandists of Gnostic heresy, as well as Marcion, the founder and propagandist of Marcionist heresy. He worked hard to defend the truths of the faith. He expelled Valentinus and Marcian from the Church because of their erroneous teachings.

Like his predecessors, Pope Pius I issued a decree that the remembrance of Lord's Resurrection should be observed only on Sundays.

Pope Pius I, who bravely served as pastor of the Church for about fourteen years, died during the religious persecution of the Roman emperor Marcus Aurelius in AD. 150 was martyred on the 5th of July.