The ideas of Copernicus were upsetting to the Catholic Church primarily because they challenged the established geocentric view of the universe, which placed Earth at the center. This geocentric model was deeply intertwined with Church teachings and interpretations of the Bible, where scriptures were understood to suggest that the Earth was stationary and central in God's creation. Copernicus proposed the heliocentric model, where the Earth and other planets revolve around the Sun, contradicting these traditional interpretations. The Church saw the heliocentric theory as "foolish and absurd in philosophy, and formally heretical" because it explicitly contradicted the literal sense of many passages in the Holy Scripture. The change not only questioned the physical arrangement of the cosmos but also challenged the theological views and authority of the Church, which used the geocentric model as a basis for understanding mankind's special place in the universe. The Copernican model implied that Earth was just one planet among others, which was seen as diminishing humanity's significance in the cosmic order held by the Church.
Furthermore, the Church’s caution was influenced by concerns about the authority of scripture and the potential for a broader questioning of Church teachings if the heliocentric model were accepted literally without more evidence and theological consideration. Hence, Copernicus' ideas were not simply a scientific challenge but a profound religious and philosophical challenge to the worldview upheld by the Catholic Church at the time.