The continuing trial of two pastors in Khartoum raises the historically loaded and still deeply relevant question of Sudan's treatment of minorities.
The Reverends Yat Michael and Peter Yen have been charged with several offences, including undermining the constitutional system, waging war against the state, and espionage.
The first two charges carry the death penalty.
The campaign group Amnesty International considers the men to be "prisoners of conscience, arrested, detained and charged solely because of their peaceful expression of their religious convictions".
The case has attracted the attention of Christian campaign groups in the US, who say the men are being "persecuted for their Christian faith".
All this fits neatly into a long-held, though occasionally exaggerated, narrative of Sudanese state oppression of religious and ethnic minorities.
According to Amnesty, Mr Michael was arrested in December 2014 after a sermon he gave in a church in Khartoum North in which he raised concerns about the treatment of Christians in Sudan.
Mr Yen was detained the following month, apparently after he had sent a letter to the Religious Affairs Office querying his colleague's arrest.
As the trial continues, it is impossible to say for sure whether the men are guilty of anything, but their vulnerability is apparent.
They come from two very obvious minorities, being Christian and from South Sudan.
The southern Sudanese voted overwhelmingly for independence in 2011, after two decades-long civil wars in which well over two million people are believed to have died.
Successive leaders in Khartoum have attempted to unify a huge and very diverse country by pursuing Arabising and Islamising policies.
This often alienated non-Arabs and non-Muslims, and together with unequal development and political repression this led to civil wars in several parts of Sudan.
The independence of the largely non-Muslim and non-Arab South Sudan did not end Sudan's problems: wars continue in Darfur, South Kordofan and Blue Nile.
Despite what Christian and other activist groups sometimes claim, religion is not the dominant factor in these conflicts.
Almost everyone in Darfur and Blue Nile is Muslim, regardless of whether they support the rebels or the government or dislike both.
The issue there is more closely linked to ethnic discrimination, with those seen as "Arabs" given preferential treatment over those perceived to be "Africans".
In South Kordofan, there are more Christians, and cases of churches being bombed in the Nuba mountains where the rebels are based.
But the Nuba people are very mixed - it is not uncommon to find Christians, Muslims and followers of traditional religions in the same family - and it would be wrong to describe this as a religious conflict.
Rebels must take their share of the blame for the various wars, though Sudan's history has taught that disenfranchised people are only listened to when they take up arms.
Yet it is hard to dispute that Sudan's treatment of its minorities was and remains woeful.
The arrest of the two pastors "is not something new for our church", the Reverend Tut Kony, pastor of the South Sudan Presbyterian Evangelical Church, is quoted as saying.
"Almost all pastors have gone to jail under the government of Sudan.
"This is their habit to pull down the church. We are not surprised. This is the way they deal with the church."
Sudan's Christians are allowed to practice their faith, and you can find churches of several denominations in Khartoum, and elsewhere in the country.
But churches have been destroyed in Khartoum, and many Sudanese Christians believe life if becoming harder for them.
In one case followed around the world, Meriam Yahya Ibrahim was sentenced to death after her brother said she had converted to Christianity, before eventually the sentence was overturned and she fled the country.
In a famous speech in late 2010, President Omar al Bashir said that after South Sudan seceded there would "be no time to speak of diversity of culture and ethnicity".
It was perceived as a direct threat to all those who did not subscribe to the regime's Islamist policies, and to all those who did not come from the dominant ethnic groups from in and around Khartoum.
President al-Bashir also insisted that "Sharia (Islamic law) and Islam will be the main source for the constitution, Islam the official religion and Arabic the official language".
That might sound logical in a country where official statistics indicate 97% of the population is Muslim; but it worried many non-Muslims and also Muslims who did not subscribe to Bashir's vision of the religion and its role in public life.
Shortly afterwards, I spoke to the Nuba development worker Nagwa Musa Konda, a Christian.
Bashir's speech had shaken her, and she predicted her home region would soon become "like Darfur", a new war in a country already wracked by conflict for many decades.
Within a few months, her prediction came true: a conflict broke out in South Kordofan in June 2011, shortly followed by Blue Nile. Those wars still rage.
Generations of governments in Khartoum, going back to the Ottoman and then British colonisers, have failed to make the country's ethnic and religious diversity an advantage rather than an obstacle.
There is little to suggest the current government, which has been in power since the 1989 coup, is willing or able to break the mould.
Darfur conflict: Key points
- Fighting began in 2003 when black African rebels in Darfur took up arms, accusing the government of neglect
- Pro-government Arab militias, known as Janjaweed, accused of responding with ethnic cleansing
- In 2008, the UN estimated that 300,000 people had died because of the war, though Khartoum disputes the figure
- More than 1.4 million people have fled their homes
- In 2010, the ICC charged President Bashir with genocide in relation to the Darfur conflict
- There have been several peace processes, but fighting continues, with numerous armed groups now active