A father who believes his son was a World War II fighter pilot in “a past life” says his Christian faith has remained in tact despite his new belief while his wife says the situation has “enhanced my belief system”.

“I am a Christian, and this has only reaffirmed the strength of my Christian faith,” Bruce C Leininger said in an appearance on Good Morning America on Monday.

“It’s a new reality,” he added.

Around nine years ago, Leininger’s then two-year-old son, James, began to have recurring nightmares of a plane crash that got worse and more frequent as time went on.

"I'd wake him up and he'd be screaming," Andrea Leininger told "Primetime Live" co-anchor Chris Cuomo back in 2004. She said when she asked her son what he was dreaming about, he would say, "Airplane crash on fire; little man can't get out."

Over time, James' parents say he revealed extraordinary details about the life of a former fighter pilot – details that eventually convinced even Bruce Leininger, who originally thought the idea of James remembering a past life was “baloney”.

“Him (James) giving us the name of the ship, the name of the man he flew with, the location where he was shot down, and then three years of hard work verifying all the details right down to an eyewitness account seeing the face of James M Huston Jr (the WWII fighter pilot) being shot down, describing the way the plane hit, matching exactly what James described. The overwhelming details were there,” Leininger recalled Monday. “I had to give up the battle.”

Though the concept of reincarnation seemingly clashes with verses in the Bible such as Hebrews 9:27, which states how a man “is destined to die once, and after that to face judgment”, Leininger said the events of the past few years had given him a “much deeper understanding of the fact that our spirit has an eternal life”.

“And we really don’t know. We still have to go on faith on what happens,” he stated. James, he said, was "just an example of a spirit deciding to rejoin us”.

Today, 11-year-old James doesn’t remember the dreams that he had shared as a little boy – a common occurrence, according to those who have come across cases like his.

But with the events still fresh in their minds, James’ parents have written a book detailing the journey of discovery that they took in trying to understand what was happening to their son and how the journey led them to believe that James was reliving the life of James Huston, a World War II fighter pilot who was killed in the battle for Iwo Jima over 60 years ago.

“Through painstaking research and conversations with war veterans and surviving family members of James Huston, Bruce and Andrea were forced to confront their skepticism and re-examine their entire belief system,” states a description of Soul Survivor: The Reincarnation of a World War II Fighter Pilot, which hit bookshelves last Friday.

“In the process, they not only managed to solve the mystery of their son’s statements. They even discovered revelations about James Huston’s life and wartime experiences that were finally to bring peace and healing to his loved ones, decades after his death," it added.

To write the book, the Leiningers teamed up with “hard-core skeptic” and journalist Ken Gross, who says he still doesn’t believe in reincarnation even after having worked with the Leiningers on the book.

“I am a secular, rationalist skeptic,” confesses Gross.

“But I have no reasonable explanation for James Leininger/Huston,” he adds.

According to a Harris Poll survey conducted late last year, approximately 24 per cent of Americans believe in reincarnation while 68 per cent believe in the survival of the soul after death.

Among Protestants, 21 per cent said they believe in reincarnation and 79 per cent said they believe that the soul survives after death.

The figures were not much different when taking service attendance into account. Even among those who said they attend religious services at least weekly, 18 per cent said they believe in reincarnation while 33 per cent of those who “never” attend services said the same.

Notably, reincarnation was the least believable item on The Harris Poll’s list of things people believe in, which included miracles, heaven, angels, the devil, ghosts, UFOs, and witches.

Topping the list was God, who 80 per cent of Americans said they believe in.