As mud-slinging between liberal and conservative Christians over same-sex marriage, women leaders and so on and so on continues, it's timely and pertinent that internationally renowned author Philip Yancey is revisiting the theme of grace - in particular, how can we extend it to one another in the face of theological difference. It's a theme he explores in his new book, Vanishing Grace. Christian Today caught up with him to find out more.

Is ungraciousness something you recognise in the Christian scene?

Absolutely; I was prepared to write books about grace by growing up in a church that used the word but certainly didn't show it – the last I heard there are something like 45,000 denominations in the world.

John characterised Jesus as coming full of grace and truth, and the Church has done a pretty good job on the truth aspect; that's why there are so many church councils and creeds and doctrinal statements, and it's the reason there are so many denominations. But I wish we competed just a little bit as much in showing grace; it takes no grace to be around someone who agrees with you; grace is put to the test when you are around people who are completely different to you, even people who you morally disapprove of.

It's so striking when you read the Gospels that the people who were most like Jesus in one way would be the Pharisees – they were well schooled, trained people – and yet Jesus attracted the opposite. He attracted the sinners, the prostitutes and the publicans; they were the ones who enjoyed being around him and followed him. It was the Pharisee types who were threatened by him, and eventually participated in killing him.

So the Church seems to be mostly good at attracting people who are like each other, not people who are unlike each other, especially that category of the "losers". Those who are morally loose don't think "I think I'll go to church, I'm such a mess" – but they did think "Oh I'll go see Jesus, because he's got something I need". I wish the Church, and I hope to help the Church understand, that what we've been given is not just to be kept in a nice little bottle that makes us feel superior, but on the contrary we're meant to spray it around.

So how do we graciously engage with one another?

I think the key is understanding who the real "enemy" is, or why we are here. We are here to combat evil and we are here to bring a message of love and forgiveness. We live in a tough world; every day you look at the news and there's sexual abuse, murder and war, and we sit around critiquing each other over the five points of Calvinism, or whatever your thing happens to be, and we forget that we need to stick together.

Understanding our mission is important; Jesus never said "go into all the world and Christianize it", he said "go into the world and make disciples, so that they can show a different way to live".

What led you to write Vanishing Grace?

I say early on in the book that in the US, things have changed rather dramatically recently. Not so much in Britain – you're either ahead of us or behind us depending on your perspective – but ahead of us in becoming a post-Christian, secular culture. And I saw these statistics about people who are outside the faith, who have no religious commitment, and in 1996, 85 per cent of Americans who are outside the faith still had a positive impression of Christians, but then 14 years later only 16 per cent did; it's a dramatic plunge. And when I saw that I thought 'What did we do in those 14 years to make ourselves so unappealing?' and that got me asking big questions: Is it really good news that we have? How does it stand up against the way other people view the world? Why are we here? How do we live? Those kinds of things, and I wanted to write a bit of a corrective for the Church – of which I am part – what we're doing wrong, and also step back and ask that question: is it really good news? Is it something that I believe the world needs and would be better off with?

When Jesus was alive, Romans were having gladiator games that make your football games look like kindergarten play! They were killing people and jeering about it, and one in three or four babies born in the Roman empire was abandoned, and yet Jesus and Paul said nothing about either one of those things. I'm sure if you asked them if it was a bad thing they would say 'Of course, it's horrendous! It's evil', but they're not there to exterminate, not there to clean up the world, they're there – and I'm borrowing this phrase from NT Wright – to show a different way of being human, and that way is the way of grace because we live in a competitive, egotistical, dog eat dog, revenge-filled world, and we know where that leads.

The quote from Ghandi – if you take the principle of an eye for an eye and a tooth for a tooth to its ultimate conclusion, then the entire world would be blind and toothless. That's the story of history and the world needs to see a different way of living.

What do you think God is saying to the Church at the moment?

I don't know about a message, but I look where God is obviously at work and it's not so much Britain and America – I sometimes liken it to stages of marriage. There's the honeymoon stage where you think everything's going to be great, and then there's the 25^th anniversary – I've been married 44 years, I've been through all these stages – and then there's the divorce stage.

So you look at Europe and it's kind of in the divorce stage; "We tried that, the churches are still here but nobody goes to them anymore, they're just museum pieces". And in America we're kind of in the 25^th year anniversary stage; we've been there done that, a lot of us go to church, we've got Christian publishers and I can make a living as a writer, but it's like a corporation; it's like Coca-Cola. We're in the religious business. We hire professionals – they sing the songs and do the sermons and the rest of us sit and watch and applaud.

But there are other parts of the world that are in the honeymoon phase and for them it really does sound like good news! They read the Bible and just start going out and doing it, and as a journalist I love going to those places, because that's where the real life is.

For those of us in the West, I think we need to get over the past; the Church has done some terrible things and you'll hear about them right away, as soon as someone finds out you're a Christian: "What about the crusades? What about slavery?" and I think our attitude should be: "Oh man, we've done some terrible, terrible things", and the reason we think they're terrible is because they don't jive with what Jesus taught us, so okay those people made mistakes but the question is "Am I doing what Jesus taught us?" and if I cut straight on that, then it'll silence a lot of the criticisms. I do look for people who are doing just that, that we can learn from.

As a 'professional Christian', how do you maintain a genuine faith?

I experience it more as a danger when I'm speaking than when I'm writing, because writing is such a soul-searching, intimate and isolated act that I would have a really hard time being false about it; I wouldn't like myself! And, my profession is a journalist – not a theologian, or a pastor – so I write a book on prayer and the first thing I do is say, "I wrote this book because I'm a terrible prayer, I don't know anything about prayer. Here's this huge topic, I'm bad at it, how can I learn to be better at it? What's it all about?" And most of my books start with questions – Prayer, does it make any difference? Where is God when it hurts? What's so amazing about grace? So I start with a question, something that's unresolved for me, and the writing of the book is the exploration. I don't know when I start where I'm going to come out.

[Being inauthentic] is more of a danger when I'm speaking. Usually when I come up with what I'm going to say, the composition phase, it is personal and vulnerable and authentic, but there have been times in those 44 years where I've just had a ferocious fight with my wife in the hotel room and left her in there and then had to go on stage. The only thing that keeps me sane is that I know it was authentic when I worked it through. It might not be entirely authentic right at that moment! But it didn't seem right to stand up there and say "I just had a fight with my wife, I don't feel like talking to you today".

It's funny how, and I'm sure many pastors could identify with this, the very act of forcing yourself to go ahead helps heal yourself in the process. Because the "professionals" aren't like a different level of human being; they're just like everyone else, but they're put on a platform or a pedestal, and the more we are vulnerable and express our doubts and struggles, I think sometimes the more the people listening can relate.

You've talked in the past about how the instantaneous nature of the internet can be unhelpful as a writer. Can you expand on that?

It's the best of times and the worst of times for writers; I am so glad I'm as old as I am and I'm not starting out now! Because on the one hand the internet is making publishing very difficult, and it's making making a living as a writer even more difficult, because people are used to free content, they're used to paying less and less and getting it in more efficient ways, so it's hard to make a living.

On the other hand anyone can publish; you could start a blog today that someone in Taiwan stumbles on tonight, it happens all the time, and so my caution about the internet is that, just like email compared to letters, it tends to be spontaneous, not really researched or thought out, just kind of out there, and over emotionalised in a way – you can certainly see that in the comments people write.

When I had to sit down and write a letter it would be more genteel and civilised, and now they just blast you right away because it's so easy. They wouldn't write, "You're a jerk" in a letter, and maybe if they did they wouldn't get to the stage of addressing it, putting a stamp on it and mailing it, so it's just freedom taken to its extreme. It's good and it's bad; I'm a pro-freedom person, but I feel called to write lengthy, researched books that hopefully can stand the test of time.

Vanishing Grace is published by Hodder & Stoughton.