Philip K Dick & Roger Zelazny 
Deus Irae 

After World War III, the Servants of Wrath cult deified the mysterious Carlton Lufteufel, creator of the doomsday weapon that wiped out much of humanity. But to worship the man, they need an image of him as a god, and no one has ever seen him. So the high priests send a limbless master painter named Tibor Mc Masters into the wilderness on a mission to find Lufteufel and capture his likeness. Unfortunately for Tibor, the nation’s remaining Christians do not want him to succeed and are willing to kill to ensure that the so-called Deus Irae remains hidden. This hallucinatory tale through a nuclear wasteland asks what price the artist must pay for art and tries to figure out just what makes a god.