DEER ISLE — Growing up in northeastern Switzerland, Mathias Rissi skied, climbed mountains and, as a young Swiss Reformed minister after World War II, pedaled a bicycle to visit parishioners scattered around his rugged parish.

Since writing an award-winning paper at the University of Basel in the late 1940s, Rissi has been scaling a different kind of slippery slope: the words and images contained in, arguably, the Christian Bible’s most misunderstood book, the Revelation of John.

The 22 chapters of Revelation (often mistakenly called “Revelations”) are found at the very end of the New Testament, and it took nearly 500 years in some parts of the church for the book to win permanent acceptance in the Christian Bible. Its images of beast, whore and dragon, seven seals and the lake of fire are unlike anything else in the New Testament.

Rissi is 75 years old now, living in retirement in a big, sunlit house tucked away off Route 15 in Deer Isle, yet the scholarly expedition he launched in the 1940s remains his passion. He has published two books and numerous articles on Revelation in English; other books have been in German, his native language and traditionally the language of theological scholarship.

He is soft-spoken, polite, and hesitant to spend much time talking about his personal life. After a few years as a pastor, he taught at a university in Switzerland. In 1963, he began teaching New Testament at Union Theological Seminary in Richmond, Va., affiliated with the Presbyterian Church (U.S.A.). He and his wife, Veronica, moved to Deer Isle soon after his retirement in 1987. A son and grandchildren live nearby.

But pull up a chair to his dining room table, pour a cup of coffee and let Rissi begin explaining a lifetime of reading and thinking about Revelation (in French, English, German, Italian, Spanish and Hebrew, besides the Greek in which the book was written). Rissi can become engaged in the conversation, pausing to define a term now and then, quoting chapter and verse from memory.

“It’s a fascinating book. It’s difficult, and not many people understand it, really,” Rissi says. “Unfortunately, our well-established churches neglect it, again and again. And that’s the reason why it went out into all kinds of sects. They use it and misunderstand it.”

Take a minute to recall all the phrases and impressions from Revelation that have spilled over into the popular imagination, and the challenge of Rissi’s task becomes clear:

The four horsemen of the apocalypse (military might, warfare, famine and pestilence).

The number 666 (in Chapter 13), which some say refers to the Roman Emperor Nero and which, just a few years ago, some tried to associate with the six letters in each word of Ronald Wilson Reagan’s name.

The whore of Babylon, who is referred to in Shakespeare’s plays.

And the seventh seal, the title of a classic film by the Swedish director Ingmar Bergman. The seventh seal (Chapter 8) refers to the end of time.

Rissi recalls that David Koresh of the Branch Davidian sect in Texas made use of images from Revelation. “In Waco, you remember, that strange man said, `I’m just studying the seventh seal and I’m absolutely sure Christ is coming in a few weeks.”‘

In the United States, perhaps the best-known use of Revelation’s mysteries has been by fundamentalist Christian author Hal Lindsey, whose book, “The Late, Great Planet Earth,” has been a best seller since it was published in 1970. Lindsey uses material from Revelation and other parts of the Bible to describe the end of human history and the start of a new era.

Even among scholars, there is tremendous difference in interpretation. Rissi parts company with many mainstream theologians who see the Revelation of John as a work designed to assure uncertain Christians undergoing persecution by the Roman Emperor Domitian, who ruled from A.D. 81 to 96.

Instead, Rissi concludes that Revelation is a book written to warn the seven important churches of Asia Minor (in modern Turkey) about the adoption of beliefs alien to the emerging Christian faith.

“The purpose of the book has nothing to do with politics,” Rissi says. “It’s not written against Rome. It’s written against heresy.”

And Revelation is not a book about the history of the world or the history of the church, Rissi says.

The author, identified only as John, appears to be a Jewish Christian, familiar with what now is called the Old Testament, the language of Jesus (Aramaic) and Greek. Scholars can make that guess based on the way the author uses language and stories. Much of Revelation needs to be read in light of the Old Testament, Rissi stresses.

Because the book appears to have been written near the end of the first century, most scholars today doubt that the “John” referred to in the book’s first chapter was the apostle John, as tradition had held. But nothing for certain is known about him.

Rissi says the way the book is written suggests that the writer was well-known in the seven Asia Minor Christian communities addressed in the book. The constant references to the seven churches there imply that he was aware of activities and problems in each community.

“He could as well have been a businessman who had [worked in] all these areas commercially,” Rissi says. “And of course as a Christian he [would have gone] from church to church.”

Rissi concludes that John wrote Revelation in A.D. 75 to 79, about 20 years earlier than some scholars have estimated.

What changed the way Christians viewed Revelation, Rissi believes, was the insertion in the late A.D. 90s of additions to Chapters 13 and 17. That made scholars conclude the book was focused on Christian persecution by Rome.

Rissi says Revelation finally won acceptance as part of the Christian canon primarily because of its concluding chapters, which focus on the ushering in of a new millennium and, ultimately, the Last Judgment.

Such vivid imagery achieved a firm grasp on the Christian imagination and is unlikely to be shaken loose.

But Rissi says the tendency to find in Revelation “what I want to find” poses a challenge to pastors and scholars alike.

“Images can always be interpreted in different ways,” he says. “It has been done again and again, and therefore we have to find out what the images really meant, originally.”

So Rissi is continuing his research from Deer Isle. He says he keeps “reading, reading and reading.” And climbing, climbing and climbing.