I have these 'gulp' moments as a junior doctor. My day is happily ticking along, everything is under control. I'm well within my comfort zone. Then BAM! I'm thrown into a desperate situation that tests me to my limits, and I never even saw it coming. I'm driven so far out of my comfort zone that I can barely see it in the rear-view mirror. Suddenly, I am overcome by the desperate nature of the situation. And yet, despite the dread eating away at my confidence, I am forced to take a big gulp and press on, because to stop or to go back would be a hundred times worse.

There was the girl who came to my clinic the day after her father had committed suicide. She was in floods of tears as she tried to explain the flurry of emotion this had caused her family. That was a big gulp moment. How was I supposed to speak any hope into her situation?

Then there was the patient I was called to visit in the middle of the night. He had been very unwell for a long time, but had taken a sudden and severe turn for the worse. As I arrived and started to assess him, he looked like his heart might stop at any moment. His wife knelt on the floor beside him, clutching his hand, begging us to keep him alive for the sake of their seven-year-old son. Another big gulp. How could I bring hope to that situation?

The reason I'm telling you about these 'gulp' moments is because I'm worried that this may be one of those moments too. My name is Freddie Pimm and I am a junior doctor living and practising in London. I'm also a Christian, and my book, The Selfish Gospel, is a brief look at the symptoms, diagnosis and treatment of one of the most complex patients I have ever encountered: the body of Christ, the Church.

You see, I believe that in many areas of the Church today, we are not as healthy as we ought to be. In some areas we are thriving; there is new life, new growth. There are people coming into contact with God and coming away changed, their lives transformed. Here, the Church is seeing transformation – of ourselves, our communities and our nation. This is the picture of the Church that Jesus calls us to see. This is Jesus' picture of health. In other areas of the church, however, we are failing to exert the same transformative power.

In January 2016, the Daily Telegraph published an article under the headline 'Church of England Attendances Plunge to Record Low'. Although in some areas of the Church we are seeing the most amazing things happen, headlines like this seem to suggest something different. They show a picture of the Church deteriorating, gradually losing our strength until we give up and breathe our last. You cannot believe everything you read in the media, but the fact that this headline exists at all would suggest that we are having a very real struggle with transformation in the Church.

Whether you feel it in the church you attend or in the communities of which you are a part, it is hard to deny that some areas of the Church are unwell. And, if the amazing pockets of transformation that some churches are seeing are lost in a sea of conformity and decline, the status of our patient – the Church – becomes even more critical indeed.

But what's that got to do with you and me?

If you are reading this at a buzzing summer festival, discussing it with your inspiring home group or waiting for your vibrant church service to start – praise Jesus! You are reading this in a pocket of transformation. You are reading this in a pocket of health! However, if your life is anything like mine, it won't take long for you to think of a place where being a Christian is counter-cultural, controversial and straight-up hard work. The Bible says the Church is the body of Christ – and it's a body with many parts. So if some parts are unwell, it is as much a problem for those who are thriving as it is for the ones just surviving.

And this is why this is a big 'gulp' moment for me: I am a relatively normal Christian guy with a relatively normal Christian story. I have a relatively normal job and I attend a relatively normal church in a relatively normal part of the country. If you want two words to sum me up, 'relatively normal' would do it! And so this is a big 'gulp' moment because I am going to try to write openly and vulnerably about issues that I feel most keenly in my life and at the churches I have attended. This is a big 'gulp' moment because, at its heart, The Selfish Gospel is a critique of myself as much as it is a critique of our Church.

The above extract has been adapted from Freddie Pimm''s book, 'The Selfish Gospel – Be transformed by giving it all' (IVP, June 15, 2017). Order the book online or in store today. Follow Freddie on Twitter @Freddie_Pimm