John Thavis, a journalist, retired Catholic News Service Rome bureau chief and St. Paul resident digs into miracles, relics and exorcism in his new book, “The Vatican Prophecies: Investigating Supernatural Signs, Apparitions and Miracles in the Modern Age” (Viking), which will be published Sept. 15. The author of “The Vatican Diaries” (Viking-Penguin, 2013), Thavis is a parishioner of St. Frances Cabrini in Minneapolis.

Q. Where did the idea for this book come from?

A. I realized there was one aspect of the Vatican that I had not covered in the earlier book [“The Vatican Diaries”] and no one’s really written about much, and that’s how the Vatican investigates the supernatural. It was always of interest to me because, of course, there is no single way the Vatican approaches the supernatural.

If we’re talking about miracles, then there’s a procedure; it’s in connection to the sainthood cause, a very, very complicated and set procedure. If we’re talking about apparitions, then it goes to the doctrinal congregation and they try basically to stay out of it as long as they can, and when they do investigate, they’re very doctrinal about it. They’re looking at content; they don’t want anything that confuses the faithful. If we’re talking about relics, then there are all kinds of mixed messages, because while the Vatican is trying to steer the Church away from venerating relics and slicing up bodies of saints, at the same time there is a resurgence of interest in relic tours.

So I saw a certain tension, not just in the Vatican, but also in the Church as a whole, between the thirst for a supernatural sign, and the Vatican’s reluctance to give endorsement to too much of this. I wanted to explain that in a book, and I wanted to explain how both approaches exist in the Church because we are, after all, a Church of miracles and a Church of reason. We walk that fine line all the time. It really hasn’t changed in 2,000 years, although it’s changed a little bit.

That’s why the epigraph at the beginning of the book is from the Gospel when the Pharisees come to Jesus and say, “Give us a sign.” It’s as if to say, “Prove to us that you are God.” In some ways, that is what the Vatican is looking out against. They don’t want people approaching or seeking after supernatural signs to prove the faith is real. They’re happy to see and welcome signs because God can do that and it helps people. What they don’t want is people going after a sign as a proof, an “I need this to believe.” That, for the Vatican, is always a sign of weak faith.

As Pope Benedict always said, private revelations, apparitions, none of these things add anything definitive to the faith. That ended with the New Testament. So, again, the reason I wrote the book is because I saw this as an area where it’s much more complicated and interesting than most people realize.

Q. You’ve lived in Rome and the U.S. and researched your book in both places. How do the approaches to miracles differ in America and Europe?

A. In Rome, you walk around, you see these “ex-votos,” gifts of prayer in thanks for intercession received. Many of these people believe they prayed and got well. That’s still present in Rome, but I believe it’s disappearing. Culturally, Rome itself, and Italy itself, is becoming much more secular. At the same time, in the U.S. there’s almost a growing interest in this type of thing.

In my chapter on miracles, one of the cases I zero in on is the case of three young people in a very small area of Kansas. They’re all young athletes, struck down during athletic competition by illness or injury, all presumed they would die, and all recovered — miraculously, in their minds, because family and friends prayed to a man they believe is a saint: Father Emil Kapaun, who was a Catholic chaplain during the Korean War. He died in a Chinese prison camp and his body was never found. He was from a tiny town of Czech immigrants in Pilsen, Kansas.

I went there, and it’s an incredible thing, because these three young people didn’t know each other. . . . It may not be something in the broader American culture that’s on the front pages, but it percolates out, and every now and then you do hear these stories. I think if you go around and talk to enough people, you’ll find almost every Catholic knows someone like that. They’re out there. There are more stories than you might think.

Q. How does the Internet change how miracles are reported or received?

A. There are so many people who believe, “I’m in contact, I’m getting messages.” When they start saying things like, “This is a message the whole Church needs to follow and believe,” that’s when the Vatican is like, “OK, bishop, put the reins on her; explain to her how this works. We don’t demand adherence. We don’t correct the Church.”

Sometimes, these people have had to be excommunicated. That’s happened. Or, more than that, the faithful need to be warned about not following these people. In the age of the Internet, that becomes very difficult, because the Church has always had a go-slow approach — go slow, be cautious, and don’t pronounce too quickly, because it will probably go away.

But in the age of the Internet, these things can go viral quickly, and soon it’s too late for the Church authorities to say, don’t listen to this person, because they already have a huge audience. It challenges the Church’s way of handling this. The Church has always said a person can have true mystical experiences and have something supernatural occur in their life. But one of the traditional ways of discerning this is that they’re under the care of a spiritual advisor, that they go slowly and carefully, that they don’t broadcast this stuff. They’re humble. Humility is a sign to the Church of the authenticity of this stuff.

Nowadays, not only is this stuff instantly available to millions of people, but the media, and in part, the people, want these visionaries to be public figures. They want them to meet with pilgrims, they want them to give us the messages, they want them to explain the messages, tell everything and be accessible. That does not really fit with the Church’s century-old tradition of mysticism.

Q. What’s the main takeaway?

A. The Catholic Church is cautious and careful when it comes to the supernatural for very good reason, because there’s a lot at stake. I would hope that people would come away from the book with an understanding that it’s sometimes a lot more complicated than it seems when you’re talking about a miracle, an exorcism or the supernatural powers of a relic. And it is fascinating.