More quotes by William Peter Blatty, The Exorcist

"As far as God goes, I _am_ a nonbeliever. Still am. But when it comes to a devil---well, that's something else."
"The child was slender as fleeting hope."
"Perhaps evil is the crucible of goodness... and perhaps even Satan - Satan, in spite of himself - somehow serves to work out the will of God."
"God never talks. But the devil keeps advertising, Father. The devil does a lot of commercials."
"We mourn the blossoms of May because they are to whither; but we know that May is one day to have its revenge upon November, by the revolution of that solemn circle which never stops---which teaches us in our height of hope, ever to be sober, and in our depth of desolation, never to despair."