Why were most of the philosophes hostile to revealed religion and to the Catholic Church?

They believed in seeking truth through reason (rather than revelation), and objected to the way that the Catholic Church had suppressed or oppressed persons who challenged or contradicted the Church's leaders and teachings.

Explanation:

The Scientific Revolution questioned superstition and traditional beliefs that had not been investigated. The philosophes of the Enlightenment championed this approach to knowledge, emphasizing the use of reason in all matters, in contrast to following superstition or unquestioningly accepting traditional beliefs.

Enlightenment thinkers also were convinced that all human beings have certain natural rights which are to be protected and preserved. So they objected to the way that the Catholic Church and its hierarchy sought to control people's freedom of thought, as well as how the Church partnered with powerful monarchs and the nobility and limited the rights of the majority of people in society.