Don Juan was described by a contemporary as "a school of Atheism." Tartuffe so stirred up the clergy that some clerics wanted the playwright burned as a heretic! Instead, he was excommunicated.
Carlyle abandoned his Christian beliefs in 1818 after reading Gibbon. After further study... Carlyle gave up the Holy Ghost and immortality, as well, adopting a Pantheism like Goethe's.