It's the opening day of Primark's flagship store on Oxford Street. People are queuing round the block to get in, and the frenzy reaches such a fever pitch when rumours spread that everything inside costs a pound, that mounted police have to be called in.

One of the successful shoppers leaves the store with six or seven flimsy brown paper bags. As she struggles to carry them all in the pouring rain, one of the bags breaks and the clothes fall to the ground. The woman looks at them for a moment then, instead of picking them up, simply leaves them there and walks on.

I hear this story, taken from Lucy Siegle's book To Die For – Is Fashion Wearing out the World, twice over the course of the 2015 Greenbelt festival. And twice it hits home. As Siegle points out, it is a chilling example of how fashion is now so disposable that it has become litter.

Peel away the layers, however, and it soon becomes clear that what we may see as something cheap and easy to discard, has touched a huge number of lives before it reaches the high street.

Katherine Maxwell-Rose, editor of Tearfund Rhythms, says in her Greenbelt talk Primania: Who's Paying for your Clothes?: "We might think that we are the first ones to get our hands on the latest bargain, but the reality is that hundreds of pairs of hands will already have touched its different parts. Seventy separate operations are required to make just one pair of trousers.

"From growing and spinning the cotton, to cutting and sewing the fabric, weaved into our clothes are the hidden tales of the people who made them. These stories that we wear on our backs, on our legs, over our shoulders are most likely to be the stories of some of the poorest people in the world."

The truth is, if we're getting a bargain – say, a top for £3 – someone else is paying the price instead. Someone like the seamstresses who only make 7p per garment.

As Katherine lists some of the horror stories that have happened at the production stage to keep prices low for Western consumers – children being trafficked into the fashion industry to work as slaves, factory collapses resulting in hundreds of deaths that could have been avoided if the pressures for fast fashion weren't so great – I start to squirm uncomfortably in my cheap-but-no-longer-so-cheerful clothes. Who knows what atrocities went into making them?

And yet I always seem to want more. As Katherine points out, "In this increasingly expensive age, fast fashion provides a comfort blanket to our stresses and squeezed bank balances.

"The cycle is addictive, with clever advertising constantly playing on our insecurities. The more we buy, the more we want; and yet as numerous studies have revealed, the more focused we are on materialistic values, the more depressed and anxious we are likely to get."

So, as Christians, what is the right response? Should we turn our backs on the vacuous, exploitative industry that is fashion?

Definitely not, according to Joanna Jepson, former chaplain at the London College of Fashion and author of A Lot Like Eve, whose talk delves into issues of women's damaged body image and how faith and fashion are inextricably linked.

"We have to engage with fashion," she says. "We can't just shun it and pretend it doesn't exist – fashion really does matter. Practically speaking, it's the fourth biggest contributor to GDP; and it provokes a huge emotional response in many of us."

For Joanna, it's about how we recover a good relationship with fashion rather than maintaining a broken one.

"You know when you eat too much and you feel slightly sick? I think it's the same kind of feeling when we are obsessing about clothes in a negative way.

"You have to really brutally look in the face your own pathology when it comes to fashion, and be able to pick up on where you're deviating and it's become something that's not about the joy of the clothes."

Like many of our relationships, the one we have with fashion is distorted and damaged – and Joanna traces our struggle with fashion and the way we look, particularly women, back to the fall.

She says it's telling that God's punishments for Adam and Eve were different in Genesis after they ate from the Tree of Knowledge: Adam is punished with having to toil on the land, therefore men's identities are rooted in externals, in their work and how they manage their territories; Eve, however, is punished with painful childbirth and being ruled over by her husband.

"So women's identities lie in our bodies, how we look, our sexuality and the space we're occupying," says Joanna.

She carries the Genesis analogy further, explaining how our fig leaves may have changed colour and shape over the millennia, but we're still using clothes to hide our shame – to hide our true selves.

"We live in terror of being exposed for what we really are. We live in terror that we will be found lacking. That's why we're still trying to hide ourselves with metaphorical fig leaves – and they can be all sorts of things, but fashion in particular convinces us we can hide our true selves and present somebody different to the world."

How then, can we restore our relationship with fashion and, beneath it, our relationship with our bodies and ourselves?

Katherine urges us to take responsibility for what we wear, and reduce the impact we have on the environment and humanity through the choices we make as consumers.

"We can either become nudists, boycotters or revolutionaries," she says. "Like all spheres of life fashion needs Kingdom redemption. We can abandon it to its own evil ways or we can create something new and wondrous."

Katherine recommends the Fairtrade clothing label People Tree, which starts with the skills the workers have and build up their collections from there, the Fashion Conscience website (fashion-conscience.com), curated ethical menswear collection Brothers We Stand (brotherswestand.com), and Gather and See (gatherandsee.com), which curates fashion for women that is either Fairtrade, recycled, hand made, eco-friendly, organic or uses small scale production.

But most of all she recommends taking control of our own decisions:

"Be a conscious consumer. Make informed choices. Look at the labels of the clothes to see where they were made and what fabrics were used. Decide where your own limits are of where you will and won't shop."

Joanna encourages us to acknowledge our own pain, our own specific issues, if we want to move forward.

"'Fig leaves', whatever form they might take, are part of the human condition. But whatever we choose to hide behind, it isn't sustainable," she says.

"We have to really look at what the wounds are that we're inflicting or are being inflicted on us. We need to become familiar with exactly what our areas of vulnerability are, and then we need to come home to ourselves – to make that journey from the voices in our heads, the image we project onto the reflection we see in the mirror, and come back to ourselves."

For Joanna, meditation has been key in making that journey home. "It's a very physical way of praying and returning to one's own body – just being aware of yourself. We come to know our inner strength.

"I don't think we'll ever turn off the negative voices; but we have to learn to make that journey back to ourselves and to who God has made us to be, and to feel at peace with our bodies."