War and a collapsing economy has left around 100,000 people facing starvation and a further one million people on the brink of severe food deprivation.
Pope Francis has called for a day of prayer and fasting for the nation on 23rd February.
Cathy Hynds, South Sudan's representative for Catholic international development charity (CAFOD), said aid has helped the country, but there's still a lot more to do.
"The humanitarian response last year, kept people from the brink of catastrophe; vulnerable families have been supported with the food they urgently needed, which has saved the lives of many," she said. "However, we enter 2018 with a crippling hunger crisis in previously stable areas of the country."
Auxiliary Bishop Daniel Adwok of Khartoum, Sudan described how "terror reigns" in the neighbouring country.
He told Christian charity Aid to the Church in Need (ACN): "The war in South Sudan has created mass displacements in many parts of the land... the destruction of the family fabric and loss of respect for human dignity."
He added: "Terror reigns in South Sudan, with warriors, government and politicians grappling for power, positions and not minding the fate of the ordinary Southern Sudanese.
"The fact that until today no one knows - the government itself does not know - how many people died in South Sudan since the start of the war in December 2013 is indicative of how the value of the human person has become of no worth in South Sudan.
"No one keeps count and it looks as if those who died of violence, some of hunger and other mistreatments were 'unfortunate' - [as if] they were in the wrong place at the wrong time."
Hynds has encouraged people to pray for an end to the conflict.
"We pray, and ask others to pray for a sustainable political solution to the conflict; to pray for the continued initiatives of churches in South Sudan on the action plan for peace, and that the needs of the people of South Sudan are met," she said.
Stay up to date with the latest news stories from a Christian perspective. Sign up to our daily newsletter and receive more stories like this straight to your inbox every morning.
