The Brothers Karamazov by Fyodor Dostoevsky explores faith, free will, and morality through the troubled relationships of Fyodor Karamazov and his sons Dmitri, Ivan, and Alyosha.
Thus Spake Zarathustra by Friedrich Nietzsche presents philosophical reflections on the Übermensch, the death of God, and self-overcoming through allegory and parables.
The Pilgrim's Progress by John Bunyan is an allegory of Christian salvation, following Christian’s journey from the City of Destruction to the Celestial City.
Beyond Good and Evil by Friedrich Nietzsche critiques traditional morality and challenges concepts of truth, religion, and power with bold philosophical insights.