why do popes change names

Popes change their names primarily as a tradition that symbolizes a new mission and role upon becoming the leader of the Roman Catholic Church. This practice began around the 6th century when Pope John II changed his birth name Mercurius, which was that of a pagan god, to a Christian name to avoid inappropriate associations. Since then, adopting a new papal name has become a way to honor previous popes or saints and to signal the new pope's priorities and inspirations for his pontificate. For example, Pope Francis chose his name to honor St. Francis of Assisi and emphasize his focus on humility and the poor. While not mandated by church doctrine, the tradition serves as a symbolic fresh start and respects the historical legacy of the papacy. The last pope to keep his baptismal name was in the 16th century, and since then, nearly all popes have chosen a new name.