Pope John I served as the head of the Roman Catholic Church from 523 to 526 AD. He is known for his efforts to promote peace and unity within the Church during a time of political turmoil in the Roman Empire. His papacy was marked by his interactions with the Gothic king, Theodoric, who was an Arian Christian, leading to tensions between different Christian sects. John I was eventually imprisoned by Theodoric due to his support for the Nicene Creed, which upheld the belief in the Trinity. He died shortly after his release, and he is remembered as a martyr for his faith. His feast day is celebrated on May 18.