I’ve read all of these books and I recommend them for anyone looking to dive deep into spirituality.
Power vs. Force: The Hidden Determinants of Human Behavior by Dr. David R. Hawkins
Mastering the Core Teachings of the Buddha: An Unusually Hardcore Dharma Book by Daniel M. Ingram
Discovery of the Presence of God: Devotional Nonduality by Dr. David R. Hawkins