from my link above:
"The great challenge for Christianity in the Sudan, especially in the southern part of the country, is closely linked to the civil war between Sudan's North and South. This war has raged intermittently since 1955, making it possibly the longest civil conflict in the world. It continues unabated, mostly outside the focus of diplomacy or the attention of international media, taking a huge and terrible human toll. Over two million people have died as a result of the war and related causes, such as war-induced famine. About five million people have been displaced, while half a million more have fled across an international border. Tens of thousands of women and children have been abducted and subjected to slavery. By all accounts, it appears to be the worst humanitarian disaster in the world today.
Religion is the pivotal factor in the conflict. The North, with roughly two-thirds of Sudan's land and population, is Muslim and Arabic-speaking; the Northern identity is an inseparable amalgamation of Islam and the Arabic language. The South is more indigenously African in race, culture, and religion; its identity is indigenously African, with Christian influences and a Western orientation.
Although Christianity predated Islam in northern Sudan, it was effectively eradicated and replaced by Islam by the early sixteenth century. It was then introduced to the southern part of the country through missionary work that was associated with British colonialism. Since independence, the South has been threatened by the policies of Arabization and Islamization. Paradoxically, the religious persecution of non-Muslims has the effect of promoting Christianity; Southerners now see Christianity as the most effective means of counteracting the imposition of Islam, especially as traditional religions cannot withstand the forces of spiritual and religious globalization.
Paradoxically, the religious persecution of non-Muslims has the effect of promoting Christianity, which Southerners now see as the most effective means of counteracting the imposition of Islam."