The Divine Invasion - Philip K. Dick

Exiled for 2,000 years God must retake the Earth from the clutches of his nemesis using a man caught between life and death as His vessel.God is in exile. The only man who can help is clinically dead. Herb Asher, an audio engineer by trade, is in suspended animation following a car accident that appears to have taken his life. As he floats in cryonic suspension he awaits his new spleen and dreams back through the last six years of his life which reveal much of his bizarre journey and the battle with Belial, the force of evil that will stop at nothing to achieve its goal.