Father John Corapi gets on a phone in his Montana office and asks someone to boost the volume. The assistant who helped arrange an interview with him had warned about this. “Speak loudly,” she said, “he’s hard of hearing.”

Father Corapi himself has never been hard to hear. For nearly two decades, his thundering voice has preached the Gospel with a forceful, meat-and-potatoes theology that’s made him among the most recognizable priests in the world.

But since August 2007, that voice has been relatively silent. At first, that was by choice — having traveled more than 2 million miles spreading the good news, Father Corapi quit public speaking to focus on writings and recordings. But just one week into that hiatus, a mysterious sickness began to ravage his body and left him mostly bedridden.

He’s recovering now and has headed back to the speaking circuit.

On Aug. 15, Father Corapi, a member of the Society of Our Lady of the Most Holy Trinity, will preach publicly for the first time in nearly two years, speaking on “The Lord and Giver of Life!” at a conference at HSBC Arena in Buffalo, N.Y.

Register correspondent Anthony Flott spoke with Father Corapi.

Though you’re a pro at communications, you don’t seem to give too many interviews. Is there a reason for that?

It is true; I haven’t given a lot of interviews over the years. But I haven’t turned down a lot, either. I’ve never looked for interviews, but if a reputable Catholic media outlet like the National Catholic Register asks me, I’m happy to do it.

At about this time last year, you revealed that you had a parathyroid tumor. How was that treated, and how is your health now?

I probably went to physicians in my area 11 times for different physicals. They did all kinds of tests. They kept diagnosing pneumonia, virus this and that, and I just didn’t get better. So I went to the Mayo Clinic and had exhaustive testing, and they did diagnose a parathyroid tumor.

As it turns out, it seems that was false. What it ended up being, of all things … [was] two things: chronic sleep deprivation and acute vitamin D deficiency — which, by the way, is an epidemic in northern climates. Most physicians still don’t know about it and still don’t routinely test for it. You wouldn’t believe how sick it can make you. The normal way to get it is sunlight. UVB rays stimulate your skin to synthesize what they call vitamin D.

Living in a northern climate, we have hardly any sun for six months. I have to take supplements, which they gave me in massive doses, and got my levels up. I’ve got the sleep deprivation pretty well under control, which made me feel incredibly better within about a month.

Did you learn anything new about suffering through this sickness?

Yes. I can still hear my grandmother’s voice saying, “Offer it up, Johnny.” And that was kind of standard teaching in those days.

The teaching hasn’t changed, but I think in many cases it hasn’t been presented to succeeding generations, and it really is at the very heart of the faith. …

One of the things I learned was my incredible weakness. I’ve always told people this: Don’t think I’m any better at this than you are. I may know the theology and I desire to be pleasing to God … but it’s not easy. It’s much easier to talk about it, but when you’re in the midst of it — when your spouse dies, when a child dies, when you get cancer, when you lose your job in the worst economy in memory, when financial difficulties close in on you — it’s easy for preachers to talk, but it’s another thing to live through the pain of the moment.

In August you will be preaching in Buffalo with what you say is one of your most powerful presentations ever on the person and power of the Holy Spirit. What makes it so powerful?

Especially in these times, I felt that people not only need education in the faith — we’ve always tried to do that — but they also need inspiration.

I find that there is a lot of — I don’t want to call it quite hopelessness — but there’s a lot of distress out there around our country and around the world.

The remedy is the Holy Spirit.

The Spirit we have been given is no cowardly Spirit. He’s the Lord and giver of life. What I want to do is take a synthesis of the Church teaching on the third person of the blessed Trinity, the Holy Spirit; I want to incorporate that into the present moment.

It’s going to be very, very relevant. It’s going to concern things that are going on today in our country. I’m going to incorporate some of the Church’s social teachings into this conference, especially components of it that deal with economic things, the danger of socialism. … I’m really looking forward to being with the people again. I’ve missed them.

I’ve heard you say that when you first were ordained many fellow priests told you that you couldn’t preach the way you do, “hitting people between the eyes with the word of God.” Yet, you pack auditoriums and receive mailbags full of letters. Why has your bare-bones, hard-hitting way been so successful?

From before I was ordained, I knew I was called to preach. My superiors confirmed that. It’s basically the only thing I’ve ever done. … If I wanted to tone it down, dull the edge of the sword, I couldn’t if I wanted to.

From the very beginning, in general, I’ve had a great, great reception and response from the good Catholic people. I know there are some who, of course, are on the other side of things, and they hate me as much as the good folks love me. I’ve never been so conscious of being loved or hated as since I’ve been a priest.

You know, I think that’s what the truth does. If you present the truth clearly, unambiguously, it will elicit radical responses one way or the other.

A great passage from the Gospels is where Jesus said, “You think I’ve come to bring peace? I have not come to bring peace, but division that will separate a house of five, three against two and two against three.” People will probably scratch their heads reading that, but it’s the truth. What does it mean? What brings division? Truth. …

Those who are ill disposed, those who are confirmed in sin, they react negatively. They’ll behave violently. Those who are well-disposed will react positively. And so that’s why it elicits such strong emotions. I’ve had death threats multiple times over the years — many times.

People can’t understand: “Why do you have security at events?” Well, the FBI told me I better take it seriously, because they do. And it’s because of the truth.

How does Catholicism in the United States compare to when you first became a priest almost 20 years ago?

When I began, I think there were more problems internally. I see the Catholic Church in the United States, and other places, too, as having learned from its existential errors. We’ve made some mistakes; I think we know it.

I think the bishops have done a good job. They’ve really tried to correct a lot of things. … I think we’re doing better in my time. It’s not fashionable to go against Church teaching anymore. We went through a phase, I think, where some people thought it was fashionable or cool or de rigueur to rebel against Church teaching, especially the morals of the Church. There was a large-scale rebellion against the Church teaching on life.

I’m one of those people who firmly believes that in the United States and Western Europe until this absolute travesty and holocaust of abortion is removed we will be able to do nothing right.

Wisdom has been removed from secular leadership, and they will not make good decisions on anything until that’s corrected. Catholic teaching is that a single abortion is homicide, and in the United States, in Europe, we have had 50 million and counting, and I would hold that’s tantamount to genocide. …

I fear for my country because of all the economic chaos we’re going through. I hate to say it, but you ain’t seen nothing until we repent and we remove that scourge from this country and from all the world. Abortion is at the root of all the hellish things that are going on.

What can we say to those Catholics who voted for Barack Obama?

Well, at this point, I’m not sure; the deed is done. I said what I could before the election.

I personally don’t believe that any Catholic in good conscience could vote for a radically pro-abortion candidate, whether for the office of president of the United States, Congress, whatever. You just can’t do it. Why? Because you become a participant in a horrible crime, and … the Church considers abortion a terrible crime against humanity.

I heard all the arguments: “Well, we can’t have a one-issue agenda.” Well, when the issue is a matter of life and death … all other issues taken as a whole — put them in the balance, and nothing adds up to the weight of sin involved in abortion. And the world is weighted down under the weight of this horrible sin, and it’s sinking into hell under the weight of its own iniquity.

Anthony Flott writes