In Roman Catholic tradition, the pope is the successor of Saint Peter, the apostle to whom Jesus Christ entrusted the care of his Church. This makes the pope the spiritual leader of the Catholic Church, administering apostolic authority and pastoral care to the faithful across the world. 

Historically, the pope’s spiritual authority has made him a key figure in Western history and civilization. Throughout the first millennium, the pope evolved from an outlaw to an accreditor of secular sovereignty to a temporal sovereign himself. Although the next millennium saw shifts in the scope of the pope’s power through the East-West Schism, the Protestant Reformation, and the Age of Enlightenment, the pope remains a significant spiritual leader in today’s society, ushering in changes that impact Christian behaviors and attitudes on a global scale. 

One relatively recent example of the pope’s impact on modern Christianity is the Second Vatican Council (also known as Vatican II), held between 1962 and 1965, which Pope John XXIII convened to modernize the Church and make it more accessible. This resulted in widespread reforms in Church practices, including the use of vernacular languages like English to celebrate Catholic liturgies. Since then, factions within the Church have struggled to reconcile the results of this ecumenical council with their political positions.