The term 'Sunday morning Christianity' has long blighted church leaders and those desperate to infect the outside world with the good news of Jesus. The disconnect between the sanctuary and the office has perhaps never been so great, and in an increasingly secular society – arguably one even hostile to Christianity – there's every chance it could get worse.

For Katherine Leary Alsdorf, former Silicon Valley exec and now founder of the Centre for Faith and Work at Tim Keller's Redeemer Church in New York, the answer lies in empowering those in the pews not just to share their faith at work, but to excel in their work itself. It is, in fact, the latter that creates opportunities for the former, she says.

Speaking at the London Institute for Contemporary Christianity on Monday, Alsdorf quoted Dorothy Sayers, a renowned novelist and playwright and one of the first women to ever graduate from Oxford University. In a collection of essays published in 1941, Letters to a Diminished Church: Passionate Arguments for the Relevance of Christian Doctrine, Sayers said "the only Christian work is good work, well done."

"If we can be people in institutions around the world, valuing work itself and doing it well, I think that's a great witness to the gospel," Alsdorf said. "We want to see people serving their work because it's worth doing...The work we do actually matters to the Kingdom of God."

Of course, the Kingdom also looks like people coming to know God personally, but having become a Christian in her 40s after a colleague shared their faith, Alsdorf is acutely aware of the dangers of trying to evangelise too intentionally. "If we teach an evangelism strategy that says the main purpose for you being in work is to evangelise, then people can feel very used," she said. People want to be known and recognised for their uniqueness, not as just another person to tick off an 'invited to church' list, and it's vital that in our eagerness to share our faith we don't reduce colleagues to targets for conversion.

Rather than focusing on evangelism strategies and ways to weave Jesus into conversations at the water cooler, we should be building genuine relationships in our workplace. "From there we can talk about what the source of our joy, the source of our hope, and what makes us get up each day is," Alsdorf said.

It's not just those working in secular industries who get this wrong. One church leader noted that pastors are often uninterested in what their congregants do during the week, and care far more about what they can offer to the church. Discipleship courses often don't pay much attention to the workplace, despite it being where most church-goers spend the majority of their time.

It was agreed that the entire purpose of the church is actually to serve those working out in the 'world', not the other way around. So instead of churches operating using the corporate pyramid, where the masses serve the few at the top, it should be turned upside down, leaving the full-time church workers at the bottom, it was suggested. "It's much more unstable, but much more exciting," one church leader said.

Alsdorf agreed. "God is building the Church far bigger than the four walls of a church," she said. "It's about people flourishing in their own environments...The world needs individuals out in the institutions already there being agents of change, and people starting starting entrepreneurial things and effecting change."

This is no mean task. "You're on the frontline of the battlefield, but you can't do it without a basecamp," Alsdorf said. Churches have to facilitate and equip their members to be effective in the workplace. "We're calling people to be out in the world but not be of it; to go to Babylon but be Daniels...by definition [that's] a challenge. Being people of the gospel in a place that doesn't know him, there's going to be opposition."

God calls us into community, and the church is part of that. It should support workers "in their rhythms of going out and coming back, [making sure] their supplies are replenished and their bodies are re-nourished, so they can go back into the world," Alsdorf said.

Other topics covered during a vibrant discussion included how to encourage workers who don't actually want to evangelise in the workplace and feel burdened by the feeling that they ought to, and the importance of celebrating small, daily testimonies that speak of God's goodness in every day life.

Alsdorf concluded, however, by noting that Christians have an incredible opportunity to counter the 'survival of the fittest' culture in the workplace, where colleagues trample over each other in the scramble to climb the corporate ladder.

"In God's economy, flourishing is not a zero-sum game," she said.

"It's not 'you flourish at my expense', or 'I flourish at your expense'. It's not like in competitive sport, where one team has to win and another has to lose. It's more like a symphony, where everyone contributes and flourishes to make something more grand and beautiful."