Shane Claiborne is no shrinking violet. Prominent speaker and bestselling author Shane heads up Red Letter Christians, a movement that is committed to living "as if Jesus meant the things he said". Consequently Shane is a passionate advocate against homelessness, war, gun violence and the death penalty. As he sees it, the Gospel of grace is a call to Christian activism, something he talked about when we met at the YMCA's recent 175^th anniversary celebrations in London.

"I have a friend who sent me a letter that said I feel very lonely in a world where there are so many unbelieving activists and inactive believers," he said with a smile.

"He was pointing out that a lot of Christians believe, but they don't always act on those beliefs in concrete ways."

All of which explains his readiness to participate in the London celebrations.

"I'm here to celebrate 175 years of the YMCA because it's not just been an organisation about words but about action and the building up of a whole generation of people from all around the world," he continued.

"Young people are very aware that politicians in many of countries have failed, and as we look at the world we have been handed from our parents we can see that it is very fragile. God cares about that, and we should care about it too."

For Shane, faith is not simply a ticket into heaven or a licence to ignore a hurting world. Faith, he believes, should give us the determination to transform the world for the simple reason that Jesus talked about the Kingdom of God being rooted on earth. It's not about "going up when we die", he observes, but "about bringing Gods dream down to earth while we live".

"We must ask: 'What does it look like to stand on the side of love in our own context in a world so full of fear?'"

"The health of any society is not shown by how the stock market is doing or how rich we are but how the most vulnerable are doing.

"And of course justice issues are all interconnected so it's impossible to separate caring for the environment from our care for the poor. The folk who suffer the most injustices are the most vulnerable people."

And so for Shane, this will inevitably mean reading the newspaper - or the latest Twitter feed - at the same time as we read Scripture, asking what it means to live out the good news of Jesus in our own particular context.

And for him, the United States is a particularly challenging context at the moment.

"We are living through some historic and troubling times," he said. "Just before I came to London I was at the border in El Paso where we have kids who are living in cages, separated from their own families, because our own administration has said they don't know if they will ever be reunited. And five days from now, following my return to the US, I will be on a march from death row to the Governor's office in Tennessee because my home state has started executing people again after ten years."

In his most recent books, Shane strongly opposes the death penalty. He's not always felt this way. In fact he was once a supporter of capital punishment; but all that has changed.

"It is the residue and legacy of our racism," he says, adding, "The states that hung on to slavery the longest are the same states that try to keep the death penalty alive."

Sadly, Shane has concluded that Christians in the US are more pro death than they are pro life. 

"We like to say that we are pro life," he observes, "but we have defined that so narrowly in terms of abortion that in the US you can say you are pro life and yet be pro death penalty, pro guns, pro military, anti environment; pretty much pro death on every other issue."

Shane would much prefer Christians to embrace a consistent life ethic, an ethic that challenges them "to stand for life from womb to tomb".

He accepts that Christianity has been an incredible force for good over the centuries, hence his readiness to participate in the YMCA celebrations. But he appreciates that people who claim to follow Jesus have done some pretty horrific things too. Jesus, he believes, came to heal the world of hatred and violence but tragically, Christians easily end up justifying it. And this is what he has concluded is happening in the United States today.

"Beyond the political crisis is a spiritual and moral crisis," he says. "The same people who led me to Jesus have led us to Donald Trump. Eighty-one per cent of white evangelicals voted for him, and many of them continue to defend him. Some of the most prominent voices in our country continue to forfeit their moral authority for the sake of political expediency. They are defending things that are absolutely indefensible."

That's why Shane reckons that Christians need to offer a different narrative, one that which challenges this "toxic evangelicalism".

"It's been said that Trump didn't change America; he revealed America," he continued. "I think the same is true of American Christianity. Trump didn't change it; he revealed it, and what we are seeing is deeply disturbing. It's been called 'whitelash', like a backlash of white identity.

"There is an identity crisis among white Americans in particular which has resulted in the oppressive fear-driven violence that has been beneath the surface but is now emboldened by the President's language."

For Shane, this is the time when Christians are called to make a radical choice.

"I stand on this promise," he says.

"Perfect love casts out fear. This is a moment in history when we have to decide will we stand on the side of love or on the side of fear."

And he clearly believes the YMCA can play an important part in all of this.

"I'm encouraged by so much that I see here," he said. "There are still things being discerned, like the role of faith in the YMCA and holding to its roots. That is absolutely vital. Keeping to the conviction that there is a deep spiritual conviction in all of us and that sin and salvation are not just personal, but public and social. We've got to hold some of these tensions because they're like blades of scissors; they only work well together."

He continued: "In the US we have been inspired by the prophet Micah, who talked of turning swords into ploughshares. We don't have many swords but we do have a lot of guns and that's why we started inviting people to donate some of the 300 million guns we possess and have been turning them into garden tools.

"In the same way we wanted to contextualize our message when we launched Red Letter Christians here in the UK. There were many things we could have addressed but one of them is the epidemic of knife violence. That's why have turned them into art.

"This is not about issues but about loving our neighbour, recognising that when anyone is hurting we are all hurting, and until we can all live without fear, until all of us are free, none of us are fully free."