Raniero's election as Pope Paschal II was marked by a backdrop of intense conflict between the papacy and European monarchs concerning the Investiture Controversy. This long-standing struggle revolved around whether the pope or the monarch held the ultimate authority to appoint bishops and abbots. Following the previous election of Pope Urban II, whose actions spurred the First Crusade, the next papacy navigated a complex political landscape. Raniero, regarded for his commitment to church reforms and moral leadership, faced an uphill battle as he took office and sought to assert papal authority over the appointment of church officials, particularly in regions where kings wielded significant influence.

During his reign, Paschal II found himself at odds with Emperor Henry IV of the Holy Roman Empire, himself embroiled in struggles of legitimacy and power. Much of Paschal’s focus turned toward aligning spiritual authority with the reforms desired by the church while simultaneously managing the expectations of powerful secular leaders. The pope's decisions would reflect a careful balance between asserting papal supremacy and navigating the intricacies of alliances and rivalries among Europe's royal families.

The Investiture Controversy not only defined the relationships between church and state during Paschal II's papacy but also contributed to the formation of the doctrines of the Catholic Church regarding ecclesiastical appointments. His tenure is seen as pivotal in recognizing the need for a clear delineation between spiritual authority and secular power, setting the stage for future confrontations that would echo throughout the Middle Ages.