Novel, first published: Del Rey/Ballantine 1981
For the last thousand years, a society of religious robots and humans has formed Vatican-17, a colony located on a planet, fittingly named End-of-Nothing, at the rim of the galaxy. This bizarre group has been engaged in a secret project, the ultimate infallible Pope, a computer Pope containing all the accumulated knowledge that can be gathered from the universe. Some of the Pope's input comes from psychic humans called Listeners who can travel mentally to other planets and record their experiences on "knowledge cubes" eventually fed into the Pope. Based on the Pope's knowledge rather than faith, the robots hope to establish a truly universal religion.
When one of the Listeners (appropriately called Mary) claims to have found Heaven, a religious crisis is precipitated. The "theological" faction of robots wants to have Mary canonized a saint, but Vatican-17 fears an end to the project if there is a fanatical resurgence of faith caused by Mary's "revelation." Into this situation comes Doctor Jason Tennyson, whose skills are desperately needed by Vatican-17 when the local physician dies, and Jill Roberts, a reporter who wants to write a formal history of the colony but is forbidden publication. Tennyson meets a former spaceman, Thomas Decker, who crash-landed on End-of-Nothing and now lives with an unseen companion, a collection of sparkling dust named Whisperer.
Decker thinks he might know where Heaven is - just before he took the lifeboat to End-of-Nothing, his ship was headed to a place similar to what Mary described. On Mary's second trip to Heaven, she is thrown out, the first time a Listener has ever encountered a direct reaction from one of the worlds.
Tennyson and Whisperer join minds and teleport to a strange world peopled by aliens who resemble mathematical equations. While Tennyson is gone, Decker is murdered by one of the robots. Concerned about the program, the Pope seeks advice from the humans. Jill and Tennyson learn the location of Heaven from the equation people and, with Whisperer's help, arrive on the planet. They meet a triad of aliens consisting of a "haystack" with thirteen eyes, a bubble named Smoky, and an octopus-like creature in constant motion nicknamed Plopper. To their surprise, the "murdered" Decker is alive - or rather his double - the original had been sent to End-of-Nothing. Founded by the Bubblies, Heaven turns out to be a Center of Galactic Studies, embarked on the same purpose as Vatican-17, but, unlike the Listeners at Vatican, Heaven collects its data physically, possessing the technology to recreate any lifeform or artifact. The Bubbly Smoky is power-mad - his secret weapon is Plopper, a kind of living atomic bomb. Tennyson and the others must get back to Vatican with proof of Heaven's real nature.
Just as Plopper explodes, Whisperer abruptly transports them all back to End-of-Nothing, including the aliens. Heaven's real purpose is explained to the robot cardinal, and Vatican's search for the truth using the Listeners is restored.
Ewald, Robert J.: When the Fires Burn High and the Wind is from the North, p.121-122