Africa's most populous nation with an estimated 129 million inhabitants, Nigeria encompasses a rich and sometimes turbulent mixture of religions -- with Muslims accounting for nearly half of the population, making Nigeria one of the largest Muslim countries in the world.

Approximately 40 percent of Nigerians are Christians and the remaining 10 percent practice indigenous beliefs.

Religion has played a major role in post-colonial Nigerian society, where there is a strong connection between ethnic and religious identity.

Islam largely dominates the country's northern region, home of the Hausa and Fulani ethnic groups. Christianity is the prevalent religion in the south among the Yoruba and Igbo tribes, although the southwesterly Yorubaland contains a more diverse group of religions. The mid-section of Nigeria maintains an uneasy neutrality, with neither religion a majority.

Throughout Nigeria, religion is a tool for social mobility, providing the means for integration into business and political circles as well as educational ones. But it also has been a source of contention, fueling violent clashes between Muslims and Christians over the past decade, primarily in the predominantly Muslim northern states.

Islam
Since the 11th century, gold traders spread the Muslim faith from North Africa to West Africa along the Trans-Saharan trade routes, inextricably linking Islam with the local economy. According to religious historians, many tribal leaders found that adopting Islam expanded their trade network and promoted them as equal partners in business transactions with Arab merchants.

As reported by a Library of Congress study, Muslim practice pervades virtually all public institutions in the north. Out of Nigeria's 36 states, 12 states have embraced the Sharia, a legal code based on the Koran and the practices of the Prophet Mohammed. The vast majority of Nigerian Muslims are members of the Sunni sect.

Public meetings begin and end with Muslim prayer. Regardless of the individual's religious beliefs, all residents are familiar with both Muslim prayers and the five pillars of Islam. Reputations of religious piety accompanied with completion of the hajj, a pilgrimage to Mecca, often yield heightened prestige.

While Nigerian law prohibits religious discrimination, conversion reportedly occurs frequently among people with political and business ambitions. In its 2006 Report on Human Rights Practices in Nigeria, the U.S. State Department noted that private businesses frequently discriminated on the basis of religion.

Christianity
The majority of Nigeria's Christian population is Roman Catholic, but the country also has a diverse group of other churches. The Christian community includes Anglicans, Baptists, Methodists, Presbyterians, Evangelists, Pentecostal Christians and Africanized sects such as the Aladura.

Roman Catholics and Methodists dominate in southeasterly Igboland, while Protestants and Anglicans maintain strong influence over Yorubaland, in the southwest.

Catholic priests accompanying Portuguese traders in the 15th century first introduced native Nigerians to the Christian faith, but yielded few long-term converts. Missions in the 19th century attained much more significant rates of conversion, in part from their role in the abolition of slavery.

Britain's colonial rule helped formalize the geographic and religious differences between the north and the south. Muslim leaders in the north prohibited Christian proselytizing, while a less central power structures in the south enabled churches to create a system of religious institutions and schools.

Promoted by the British colonial government, missionary schools produced an elite class of interpreters and civil servants.
  
Since full independence from British rule in 1960, many Catholic and Protestant congregations began to include native music and dancing in their services. Several independent movements have also cropped up to create a Christian faith that relates to Nigerians culturally, including sects that have interpreted biblical passages as supportive of the native practice of polygamy.  

Indigenous belief
Although a minority of the population still adheres to indigenous practices, they continue in Nigeria, especially in the southwestern region. Nigeria's native religious beliefs tie genealogical descent to a particular site, legitimizing claims to land, resources and leadership. According to religious scholars, the theology combines ancestor worship with the worship of primordial spirits, or the supernatural entities inhabiting a particular locale. Geographical markers, flora and fauna often embody these entities.

Regular adherence to prayer and other forms of ritual worship are thought to protect followers from misfortune, and many believers use charms and talismans to ward off evil.

Throughout Nigeria, traditional beliefs have fused with imported religious tradition. It is not uncommon to find Muslims and Christians carrying out ancient religious rites -- such as wearing amulets -- although younger generations deem compliance with old traditions as renunciation of the newer faith.

Sharia law and religious violence
Religious violence has been a primary source of instability for Nigeria over the past decade.

Since the country's return to civilian-ruled democratic government in 1999, at least 15,000 people have been killed and hundreds of thousands displaced due to numerous religious, ethnic and political clashes.

The religious violence can be traced to the adoption of Sharia, or Islamic religious law, in the predominantly Muslim northern states.

The Nigerian constitution of 1999 provides a framework for the coexistence of Nigeria's two main religions. The constitution allows each state to make its own laws and says the majority Muslim states may use Sharia code.

The initial introduction of Sharia law sparked riots by Christian groups in northern states who feared they would eventually be prosecuted under Sharia, despite the constitutional assurance that the courts only applied to Muslims.

The first large-scale riots occurred in the Kaduna state in May 2000, when over 2,000 people were killed following the state government's application of Sharia. Tension over the implementation of Sharia continues today.
  
But Sharia has not been the only factor for increased violence between the religious groups. Protection and acquisition of political power and resources have also caused problems between the country's Christians and Muslims.

In 2001, more than 2,000 people were slain during riots in the majority Christian city of Jos, which started when religious factions clashed over the appointment of a Muslim government official.

The most deadly conflict of the past decade occurred from 2001 to 2004 in the Plateau State, in the center of the country, which endured a series of reciprocal attacks by Muslim and Christian workers and militias over the control of valuable farmland. In the last year of fighting, before the government intervened in 2004, violence in the state displaced 258,000 people and left 1,000 dead, according to the United Nations.

Sporadic clashes have ensued, fueled in part by politics.

"Splits within the government of Nigerian President Olusegun Obasanjo and increasing jockeying for power have seen a rise in the number of political assassinations and a general sense of insecurity across the country," stated the Internal Displacement Monitoring Centre in a September 2006 report.

-- Updated by Jonathan Brand for the Online NewsHour