Falkirk is just close enough to home that I've followed the stories of the shenanigans surrounding the selection of a new Labour candidate there with some interest. Not with enough interest to decide who's right and who's wrong, or to come to a view on whether this does represent an illustration of a fundamentally broken relationship between party and unions, or something far more local and less interesting, but with some interest - and at one point at least, with considerable surprise.

I was listening to a radio discussion on Monday and the subject of numbers came up. The journalist was making the point that the number of disputed membership applications is tiny – a couple of dozen or something. In passing she commented on the number of total members in the local party before the recent sudden influx.

She said the membership was fewer than a hundred.

This surprised me, not because I thought that local political parties had far bigger memberships than that – I've been a member of one in the past; I know – but because of the connection with the debate. The local membership were to elect a candidate for the safe – utterly safe – Labour seat. In effect, those hundred people got to choose a Westminster MP. And, given the seat is safe and likely to remain so, an MP who would serve a lengthy term and so probably at some point would rise through the ranks to ministerial office.

Fewer than a hundred people.

Of course, this is not a Labour problem. Every serious political party in the UK has safe seats, and I assume that in each case the local members, who will number similarly, will get to choose their MP. According to a Guardian report published in April 2010, the Electoral Reform Society (who, admittedly, may not be totally disinterested) classed over half of Westminster seats as 'safe'. This suggests that the majority of our parliamentarians are, effectively, chosen by groups of fewer than a hundred people.

My point here is not to advocate for proportional representation – we had that referendum, and it failed – or to complain about our politics, which we should always remember are, for all their problems, spotlessly clean and totally transparent in comparison to almost anywhere else in the world. Rather, I was struck by the power that a few people can yield if they want to, and if they understand the system.

Margaret Mead, an American anthropologist who gave her life to understanding how societies and cultures actually function around the world, reputedly once said: "Never doubt that a small group of thoughtful, committed citizens can change the world. Indeed, it is the only thing that ever has."

The history of the Christian Church – our history – is littered with little groups who have changed a community, a nation, a culture, the world. Jesus died and rose with 11 male followers and a small number of women in his close community; there may have been others, but 40 days later when he ascended, his followers numbered only 120 (Acts 1:15). That little church did a reasonable job of world-transformation! In our own British evangelical history we tell stories of the Clapham Sect - William Wilberforce; Zachary Macaulay; Hannah More; and the rest – and of their campaigns over the slave trade.

Small groups of people can change the world. It requires vision. It requires courage. Sometimes it requires an understanding of where the levers of power lie. But it does not require a mass movement – fewer than a hundred people in Falkirk will do.

Of course, we know a truth that Margaret Mead's quote ignored. In the words of John Knox, perhaps penned near Falkirk: "A man [or woman] with God is always in the majority." Mead tells us something important about the way human society works: it really is the small, committed groups who make the difference. Knox tells us something even more important about the direction of history: God is working to bring His Kingdom of justice and joy, and invites Christians to work on that task alongside Him. Working with the grain of history will be easy work.

Steve Holmes is a senior lecturer of theology at the University of St Andrews, Alliance Board member and chair of the Theology and Public Policy Advisory Commission (TAPPAC)