"The most frightening experience of the war is the noise of the Antonov bombers, which people can recognise from a distance. It freezes and paralyses them psychologically. Where the bombs will drop is not known; who will be killed is not clear. It inflicts panic, not just physical destruction."

Bishop Caesar Mazzolari of Rumbek knows what he is talking about. "We were severely bombed almost daily between about June and October last year," he told me. "They usually attack the market place so there will always be victims. They are mostly cluster-bombs, which land and splinter and hit you like heavy blades. They could take your head or limbs off. But sometimes the clusters are made of anti-personnel mines, and people find them afterwards in the fields – or children think they are toys and pick them up and lose an arm, or their lives."

Bishop Mazzolari’s diocese has been "warzone number one" in this civil war which has been ravaging southern Sudan for the last 18 years. It was the 1983 introduction of Sharia, or Islamic law, which triggered rebellion in the animist and Christian south and led to the terrible fighting which has already cost over two million lives – but the real reasons behind the war are manifold. It is cultural: the Arabs against the blacks – or "slaves" as they call them. It is about resources: the wealthy but arid North wanting the oil and water of the fertile South. And it is religious: the Muslims against the Christians. "The Arab government says it’s a holy war," one parishioner told me. "We’re not against any religion, we’re just fighting for our rights." As a result, their suffering is immense: thousands die every year, there is scarcely any medical aid and education is minimal, often at the hands of dedicated but untrained teachers.

And family life is being destroyed. In every town I visited, the lack of men was painfully striking. "I wouldn’t hesitate to say that it is almost 75 per cent women here," said a priest in one parish. "So many men have died and the SPLA [Sudan People’s Liberation Army] is still conscripting. They go to the villages and arrest the young men and take them to fight." The men and boys who do go may not return for years – if at all. Sister Jacinta Dagbaaboro lives in Tombura; her brother Peter went to fight in 1991. "He passed back through here in 1999, but then went again. We don’t hear much, sometimes only once or twice a year. It is difficult for us to know when someone has died. Sometimes you hear it after a long time – but you don’t get news easily from the frontline."

A large number of young men in the South join the army out of a fervent belief in the cause, but others go simply as a way to get enough food, or out of a sense of revenge: everyone has lost someone. Meanwhile conscription is widespread enough for those who do not want to fight often to be forced into hiding. "Many boys over 16 who know the army is coming will go and hide," explained Sr Jacinta. "Otherwise they are taken whether they like it or not. If the boys say No, the army just takes them anyway if they need them."

Yet the majority of those killed are not even soldiers. "Thousands are dying every year with this war," a local priest told me. "There are those who die in action, but also innocent civilians caught in the crossfire. And many will die of hunger, drought and starvation caused by the war. We don’t have journalists coming here to cover these incidents. I have the impression that the West is easily convinced by Khartoum." His words were echoed by Bishop Mazzolari, who recently sent out urgent press releases in an attempt to move the Western world over the plight of the many thousands of displaced people in his diocese. The Bishop reported that their homes, food and property were burnt, their cattle raided and they now live far from any source of water, in utter poverty and isolation. "These people are on the brink of death," he wrote. "In the evening, you can walk in any village of the area and you do not see fire burning outside their huts… there is no cooking to be done, because people do not have food to cook any more, even for their children."

Bishop Mazzolari accused the international community of "ignoring this tragedy", and this sense of abandonment was something I encountered frequently among the southern Sudanese. "We are surprised and disturbed and worried," said Bishop Joseph Gasi. "Why is the international community not taking note? It looks as if we are not part of humanity." For Aid to the Church in Need, pastoral aid for Sudan is a priority, and everyone was desperate to tell us their story so that we might carry their cries for help back to the West. "Your coming to Africa shows us that we’re not forgotten. That people still think of us," said Fr Mark Kumbonyaki of Mupoi parish. "We’ll never forget you, and that you followed us into the bush to see us living in this poverty."

And yet despite the hunger, displacement, war and disease, the Church is thriving and growing in southern Sudan, with the faith central to the lives of the country’s Christians. The first group of displaced people reached Macar-Abiak last September, having walked for 17 days and nights to reach the camp; some had died en route from thirst, hunger or sickness. Today they still have to walk for two hours to get water, and the adults spend all day looking for wild fruit so they can provide food for their children. Yet one of the first things they did after they arrived was build themselves a chapel where they could meet together and pray, carving a cross on a tree and making benches out of thick branches.

This devotion and spiritual strength can be witnessed throughout the country. "The faith has grown so fast in Sudan and become much deeper in the last ten years," one young priest, Fr Galdino, told me. "Every day, people are coming to restart their sacramental life and so many came back to the faith with our Jubilee year programmes – some even brought their old witchcraft instruments with them to burn!"

Fr Galdino is one of just 12 priests in the huge diocese of Tombura-Yambio. The people had wanted to build a cathedral for the diocese, dedicated to Christ the King, but the war suspended their plans. Today their brick chapel is only large enough for the 300 or so who attend the 6.30am Mass on weekdays, but in order to accommodate everyone on Sunday they have to worship in their "Green Cathedral" under the trees.

I was informed that Mass was at 9.30am, but although I arrived before nine the music and singing had already started, and when I left after Mass had finished at 12.15pm it was still going on. "The people are enthusiastic," said their Bishop, Joseph Gasi. "They pray and dance like David in the Old Testament. Marriages are very numerous, and devotion to the Sacred Heart is flourishing. The Lord is still with us and encouraging us."

Regardless of their poverty, they all dress smartly for the highlight of their week, and give ample reinforcement to Africa’s reputation as "the singing and dancing Church". As another bishop told me: "In church we give them the only social event where they are at peace – they don’t want to go home. They want to keep singing until the sun goes down."

Yet whilst most Masses pass without interruption, there is no guarantee of safety just from being in a church. Indeed, in some of the worse-hit areas of southern Sudan’s battlefield, it is one of the least safe places to be. As Bishop Erkolano Lodu of Yei admitted, it is "always a risk to life" for someone to attend Mass. "There is high attendance at church celebrations, but in Yei we are bombed almost every Sunday, so as to scatter the people at Mass. Sometimes we have to celebrate at night. The government has chosen Sunday as the best day to bomb the churches because they are full.

"We spend one hour in the trenches hiding from the plane, and then come out to see the destruction – and sometimes death. We have been losing property for years, so we don’t mind that; but human life is more precious to us. Sometimes it happens more than twice a week: we are being bombed and humiliated. We have no way to defend ourselves. They want to destroy and reduce the faith to nothing."

But it is a vain ambition: the faith and trust of these forgotten Catholics will not be crushed. After Mass one day, an old parishioner stopped me to talk. "We are suffering so much here in southern Sudan, and we do not know when this war and poverty will end," he said. "But we put our lives in God’s hands. God is mighty and we are praising Him."

Photo caption: Sunday Mass in the 'Green Cathedral' in Yambio parish.

Cecilia Bromley-Martin works for the Catholic charity Aid to the Church in Need