Anthony Wallace, author of “The Old Priest,” has a complicated relationship with the Catholic Church.

“I really like the part [in the book] where the priest thinks he changed into a goat after taking mushrooms,” he said.

Although Wallace trudged through years of grammar school under the cold glower of nuns, he also had a much more constructive experience at a Jesuit-run high school. These are two aspects of his religious education that have a place in the book.

“There are many different levels layering the story,” the Boston University professor said of the collection. “On one level, it’s allegorical about the Catholic Church and my unresolved relationship with it.”

Wallace, a Philadelphia native, recently won the Drue Heinz Literature Prize, which is sponsored by the University of Pittsburgh Press. He said it’s the most prestigious prize in the English-speaking world for an unpublished collection of stories. The honor carries a cash award of $15,000 and publication by the University of Pittsburgh Press. Drue Heinz, the widow of H.J. Heinz II, sponsors the competition, which began in 1981.

“Nothing better could have happened for me and my writing,” he said.

Wallace was selected from a pool of more than 350 entries. When he first heard the news, it took a moment to register with him.

“I played the answering machine when I got home from work,” he said of the life-changing moment. “I just sort of stood there and then started screaming.”

Amy Hempel, an award-winning author who chose Wallace’s entry for the award, praised “The Old Priest” as “a powerhouse that has the scale and scope of a novel.” And even though the characters are fictitious (Wallace said the priest is based on an influential Jesuit he met in his schooling) they ring with humanity and realness.

Hempel said the characters are “people who appreciate simple pleasure while making mistakes they have made before and will likely make again. For all the unsavory behavior, there is a moral core in many of these people’s lives.”

The manuscript, as works of fiction tend to do, evolved into something much more potent than originally intended after years of being rejected for publication.

“The story, itself, started as a portrait of somebody I knew. But then it grew into something else, something more complicated,” Wallace said.

Despite this complication, his stories encompass a particular set of themes.

“The stories in ‘The Old Priest’ have to do with time and memory, and I think there is a pattern in which they open out beyond ordinary daily time into something larger — the present moment perhaps, but a larger conception of it,” Wallace explained.

Wallace said it’s largely about coping and moving on, something the narrator of “The Old Priest” tries to do painstakingly. And like so many people, the narrator is conflicted with religion and the weighty ideals religion bears.

“‘The Old Priest’ talks about eternity as a place that contains everything that has ever been — every lost dog, every broken watch and every burnt dinner,” Wallace said.