The Progeny of Angels - Book 3 the Sphere of Higher Knowledge (The Progeny of Angels)

The earth has been uninhabitable for decades, but now humanity has returned to the planet. Mankind, though intellectually advanced has become spiritually sightless and bound by fear and insecurity and mankind's survivors have grown apart into two tribes: the spiritually enlightened Otom, living in brotherhood with the ocean-dwelling Mers, and the unemotional, strangely youthful Scientists, who live in their city beneath the ground. The Otom and the Scientists have the opportunity to meet and learn from each other. But the Otom must reach enlightenment if they are to survive, and some of the Scientists have plans that threaten their goal.