These are my top Spiritual Books of all time (Not in order)
1. The Art of Peace (Morihei Ueshiba)
2. A Course In Miracles
3. Conversations With God (Parts I-III)
4. Yoga Sutras of Patanjali
5. Tao Te Ching (Lao Tzu)
6. The Book of Secrets (Deepak Chopra)
7. The Dhammapada
8. An Introduction to Zen Buddhism (D.T. Suzuki)
9. The Upanishads
10. The Bible
11. The Quran
12. The Gnostic Gospels
13. The Talmud
14. The Bhagavad Gita
15. The Autobiography of a Yogi (Paramahansa Yogananda)
16. The Key to Theosophy (HP Blavatsky)
The Key to Theosophy
17. Esoteric Christianity (Annie Besant)
18. The Kybalion or Hermetic Philosophy (Hermes Trismegistus)
19. The Zohar
20. The Enneagram
21. Da Vinci Decoded (Michael J. Gelb)
22. The Alchemist (Paulo Coehlo)
23. Varieties of Religious Experience (William James)
24. Mysticism (Evelyn Underhill)
25. The Celestine Prophecy (James Redfield)
26. The Master Key System (Charles Haanel)
27. As A Man Thinketh (James Allen)
28. The Secret of The Ages (Robert Collier)
29. The Phenomenon of Man (Pierre Tielhard de Chardin)
30. Fully Human. Fully Alive (John Powell)
Those are just some of my top favorite spiritual books of all time that I keep on reading and studying again and again and again without end. What's yours?