Gelasius I

Pope Gelasius I is noted as one of the most significant popes of the early Church, recognized as the first to be officially called the 'Vicar of Christ.' He developed the influential Doctrine of the Two Swords, asserting the distinct roles of the Church and state, and played a crucial role in addressing the Acacian Schism, emphasizing the supremacy of the Roman Church. Furthermore, he established St Valentine's Day, intertwining Christian and pagan traditions, solidifying his legacy within the Church.