Religion

Arthur Schopenhauer saw religion as "the metaphysics of the people". 
He thought Christianity, Hinduism and Buddhism were, at the core, the same. For him, they all share some truths, but present them covered in mythology, stories, fables, and generally convoluted explanations, while philosophy (in particular, his philosophy), explains those truths directly, through reason and arguments.
He had a high esteem for Hinduism and Buddhism, and although he spoke good things about Christianity, he always thought of it as inferior to the other two.
Schopenhauer also mocked how the Church had tried several times to demand that philosophers' conclusions accord with its doctrines.