I HEARD the drumming first, then the singing. I was riding with the Bishop of Akot, the Rt Revd Isaac Dhieu Ater, into his see city, South Sudan, on a Sunday afternoon. As we came around a corner, I saw the source of all the noise: it was a procession of Anglicans, come to welcome their bishop, and offer an escort back to the cathedral. Bishop Isaac and I climbed out of the minibus taxi we were riding in, and took our place in the group.

Akot may be a cathedral city, but it is barely more than a modest market town. There is a single stretch of road, lined on each side by a few shops, tea stands, and a taxi rank. On this Sunday afternoon, our procession of two dozen people was the most exciting show in town.

As we walked down the road, I was acutely aware that everyone - I mean, everyone - was stopping and staring at us. The energy with which we had been greeted had not waned. Our drums, bells, singing, clapping, flag-waving, and sporadic ululation made for quite a show.

"Well, aren't we making a big deal of ourselves!" I thought with embarrassment. But then I realised that this was precisely the point. Processions are not simply an expression of the joy and hospitality that people might be feeling on a particular occasion. They are an evangelistic tool: "Hey!" we were saying, in effect: "We've got something good going on here. Come and join us!"

As I realised this, I started to get into the swing of things. I smiled and waved to the onlookers. I shook hands with the children who shyly came up to see me. At one point, we stopped before a group of soldiers, so that Bishop Isaac could pray with them. Before long, I was feeling like nothing so much as a small-town mayor, marching in parade on the way to a civic service.

Christianity is a public faith. From an early time, Christians realised that faithfulness to what Jesus had taught them meant that public action was necessary. The early Christians preached on Pentecost, for instance, and defended themselves in front of hostile crowds. You couldn't be a Christian and keep it to yourself. Anyway, why would you want to?

Contemporary society in the Euro-Atlantic world presses people of faith to confine their religious views to the private, individual sphere. Publicly expressing a firm conviction is hardly believable any longer in a society weakened by corrosive irony and depressing hypocrisy. Christians are sometimes complicit, interpreting the gospel primarily in terms that emphasise personal commitments.

The Anglicans in Akot are not unique in their penchant for public procession. It is a feature of the faith of the Dinka people across South Sudan. I have had similar experiences in other dioceses. In remote villages near the Nile, I have been met by processions of hundreds of Christians, marching and singing with near-militaristic precision.

In truth, by the fifth or sixth procession in a weekend, the experience can become a little wearying to one unaccustomed to such energy. But I give thanks for them all the same, for the way they challenge me to remember the public nature of the Christian faith. Our proclamationof faith may not involve drums or ululation, but the message remains the same.

"Hey! We've got something good going on here. Come and join us!"

The Revd Jesse Zink is Assistant Chaplain at Emmanuel College, Cambridge, and author of Backpacking Through the Anglican Communion: A search for unity (Morehouse, forthcoming).