In the Central African Republic, Muslim Seleka rebels and Christian vigilante groups have slaughtered civilians with abandon since late 2012. Between December 2013 and September 2014 alone, over 5,000 people died in the violence.

But when Pope Francis arrived in the capital, Bangui, on Monday, he was greeted by Muslim fighters leaping from pickup trucks, wearing T-shirts with his image on them. 'Christians and Muslims are brothers and sisters,' he said.

A colder welcome awaited him on his return to the Vatican. A trial over two journalists' use of leaked documents has placed the Catholic church at the centre of a corruption and censorship scandal.

Gianluigi Nuzzi and Emiliano Fittipaldi have been charged with exerting pressure to procure and publish confidential material after they wrote books alleging corruption at the Vatican based on leaked documents. If convicted, they could be sent to prison for eight years.

Their research suggested financial mismanagement was rife. Auditors in 2013 spoke of 'a complete lack of transparency in book-keepingIn one example, Nuzzi said it cost the Vatican an average of 500,000 each time it researched a saint.'. Some cardinals lived in expensive properties rent-free and generated huge expenses billsOne cardinal's tab for a helicopter ride in 2012 was nearly 24,000. Another senior official in the Vatican state administration also allegedly knocked down a wall separating his flat from that of an elderly neighbour who had been taken to hospital.. And about 67% of the funds donated to a Catholic charity were spent on Vatican bureaucracy.

Nuzzi says 'a true battle between good and evil' is underway in the Vatican, as the Pope attempts to address the problems in the face of fierce resistanceThe refusal to comply or go along with something. . The journalists add that their trial is an attack on press freedom. 'In no other part of the world, at least in the part of the world that considers itself democratic, is there a crime of publishing news,' says Fittipaldi.

The Catholic church has faced high-profile scandals before. Pius XI and XII were criticised for failing to oppose the Nazis' political and social aims and helping some war criminals and collaborators to escape Europe after the Second World War. And Francis's predecessor Benedict XVI was accused of suppressing investigations into widespread allegationsThese have emerged since the 1980s. In the new century alone, abuse has been uncovered in at least a dozen countries. Benedict has denied suppressing investigations. of child abuse.

Pope Francis has been widely lauded since taking office in 2013; a book by Austen Ivereigh calls him 'The Great Reformer'. He dresses and lives modestly and mixes with the world's poor and vulnerable. He has begun to deal with sex abuse and made groundbreaking interventions in the debate on the environment. If anyone can reform the church, he can.

But perhaps he only looks good in comparison to his predecessors, and the church is institutionally corrupt. Catholicism, by nature, is based on an unquestioned hierarchical order. Its most senior officials claim their authority from God and are impossible to hold to account. Scandals will keep happening as long as their positions exist.

Book-keeping - In one example, Nuzzi said it cost the Vatican an average of 500,000 each time it researched a saint.

Expenses bills - One cardinal's tab for a helicopter ride in 2012 was nearly 24,000. Another senior official in the Vatican state administration also allegedly knocked down a wall separating his flat from that of an elderly neighbour who had been taken to hospital.

Resistance - The refusal to comply or go along with something.

Widespread allegations - These have emerged since the 1980s. In the new century alone, abuse has been uncovered in at least a dozen countries. Benedict has denied suppressing investigations.