Attitudes towards church authorities;
Bellarmine was, in actuality, THE Church authority. As the Chief Theologian, he had to troubleshoot many of these disputes, and he was not fond of things that threatened the status quo.

" the seventy-four-year old Cardinal Bellarmine "was no friend of novelties"  (although, unlike some of Galileo's other detractors, he had at least looked through a telescope and given--in 1611--an audience to Galileo).  In his innate conservatism he saw the Copernican universe as threatening to the social order.  To Bellarmine and much of the Church's upper echelon, the science of the matter was beyond their understanding--and in many cases their interest.  They cared about administration and preserving the power of the papal superstate more than they did getting astronomical facts right." (>Source<) This excerpt shows that Bellarmine was friends with several of the upper-echelon church members, and he stood to benefit from their status within the church. Thus, the status quo must be held.