It was an Albigensian Crusade, not an Inquisition.
Christendom couldn’t help but be duplicitous because Jesus had led a counterculture, whereas Christianity became the dominant, imperial culture in the West. For centuries, the Church danced around that internal conflict until the Protestants broke up the Catholic Church with a reformation. Why was there a reformation if the Catholic Church wasn’t corrupt?
As to that corruption, you can argue with the Catholic Encyclopedia about the state of the Church at the time of the Reformation:
“Gradually a regrettable worldliness manifested itself in many high ecclesiastics. Their chief object — to guide man to his eternal goal — claimed too seldom their attention, and worldly activities became in too many cases the chief interest. Political power, material possessions, privileged position in public life, the defence of ancient historical rights, earthly interests of various kinds were only too often the chief aim of many of the higher clergy. Pastoral solicitude, the specifically religious and ecclesiastical aim, fell largely into the background, notwithstanding various spirited and successful attempts to rectify the existing evils.
“Closely connected with the above were various abuses in the lives of the clergy and the people. In the Papal Curia political interests and a worldly life were often prominent. Many bishops and abbots (especially in countries where they were also territorial princes) bore themselves as secular rulers rather than as servants of the Church. Many members of cathedral chapters and other beneficed ecclesiastics were chiefly concerned with their income and how to increase it, especially by uniting several prebends (even episcopal sees) in the hands of one person, who thus enjoyed a larger income and greater power. Luxury prevailed widely among the higher clergy, while the lower clergy were often oppressed. The scientific and ascetic training of the clergy left much to be desired, the moral standard of many being very low, and the practice of celibacy not everywhere observed. Not less serious was the condition of many monasteries of men, and even of women (which were often homes for the unmarried daughters of the nobility). The former prestige of the clergy had thus suffered greatly, and its members were in many places regarded with scorn. As to the Christian people itself, in numerous districts ignorance, superstition, religious indifference, and immorality were rife.”
