(Note: I posted this recommendation in another forum to a specific person, but I'm impressed enough with the book to recommend it in a more general way.)

"The Mystic Christ: The Light Of Non-Duality And The Path Of Love According To The Life And Teachings Of Jesus" by Ethan Walker III. Not only is it about the ego and non-duality, it's about universality. Very deep, very well researched. Might take a few reads before you fully digest it all, it's just that kind of book. Definitely worth acquiring if you're at all interested in Gnostic/mystical Christianity, or, rather, in the person of Jesus and the idea of Christ-consciousness that transcends orthodoxy and organised religion.