On Chasing Brad Through Purgatory — Stephen Benatar

Two men are involved in a car crash: Brad dies, and Danny -- who can't stand the thought of living without him -- kills himself, convinced that with so little time having elapsed between their deaths, he'll be able to catch up to Brad on his way to Judgment. The novel becomes a modern Pilgrim's Progress, detailing the tests inseparable from a journey through purgatory.