Saint Pius I

"S. Pii I Papæ et Martyris" is Latin and refers to Saint Pius I, who was a Pope and Martyr. He served as the Bishop of Rome (Pope) from around 140 to his death in 154 AD. He is considered a saint in the Catholic Church. His feast day is celebrated on July 11⁷. The phrase "S. Pii I Papæ et Martyris" is often seen in liturgical texts and calendars.

Here are some more details about his life and papacy:

- **Birth and Early Life**: Pius I was born in Aquileia, Venetia, in Italy. He was formerly enslaved, according to his supposed brother, the Apostolic Father Hermas.

- **Papacy**: As the successor to St. Hyginus, Pius I continued the fight against gnosticism, a religious movement teaching that matter is evil and that emancipation comes through spiritual truth attained only by revelatory esoteric knowledge. He also combated the Marcionites, followers of a heretical Christianity proposing a doctrine of two gods as taught by the semi-gnostic Marcion.

- **Legacy**: Pius I is considered to have opposed both the Valentinians and Gnostics during his papacy. He is also said to have decreed that Easter should only be kept on a Sunday. Pius I is also said to have built one of the oldest churches in Rome, Santa Pudenziana.

- **Martyrdom and Sainthood**: The claim that Pius I was martyred is unsubstantiated. He is considered a saint by the Catholic Church and the Eastern Orthodox Church. His feast day is celebrated on July 11.

(1) St. Pius I | Biography, Papacy, Feast Day, Death, & Facts. https://www.britannica.com/biography/Saint-Pius-I.

(2) Pope Pius I - Wikipedia. https://en.wikipedia.org/wiki/Pope_Pius_I.

(3) Pope Pius I - New World Encyclopedia. https://www.newworldencyclopedia.org/entry/Pope_Pius_I.