Whereas ethnic cleavages generally remained dormant, religious sectarianism emerged as the most potentially explosive social division. Islam and Christianity spread rapidly in the twentieth century at the expense of indigenous religions. About half of all Nigerians were Muslims in 1990, most of whom lived in the northern two-thirds of the country. About 40 percent were Christians, residing predominantly in the south, and particularly in the southeast. Since 1980 there had been several outbreaks of sectarian violence, resulting in thousands of deaths, injuries, and arrests, mostly attributable to sectarian tensions and also to some fringe quasi-Islamic groups.

The first and most dramatic eruption in a series of religious disturbances incited by the Maitatsine, or Yan Tatsine, movement was an eleven-day emergency in Kano in late December 1980 (see Islam , ch. 2). Led by Alhajji Muhammadu Marwa (alias Tatsine or Maitatsine), followers of this heretical Muslim sect of perhaps 3,000 persons opposed secular authority, were willing to use violence if necessary, and demanded absolute obedience to Marwa. The Kano riots were suppressed by the army and the air force after the police failed to restore order. More than 4,000 deaths resulted, including that of Marwa, and 1,000 arrests, including 224 foreigners.

In addition, there were disturbances caused by another Muslim movement known as Yan Izala that began in Zaria and Kaduna in the 1960s. This group, which created unrest in the early 1980s, protested innovations in Islam and was particularly opposed to the Sufi brotherhood movement.

Renewed rioting in Kano in July 1981 that destroyed or damaged several state government buildings was attributed to Muslim extremists opposed to the proposed removal of the emir of Kano.

More riots by Maitatsine followers broke out in Maiduguri in late October 1982 and spread to Kaduna, where thirty-nine sect members were killed by vigilantes. The official death toll was 188 civilians and 18 police (mostly in Maiduguri), and 635 arrested, but the commission of inquiry afterward concluded that deaths probably exceeded 500. The sect was banned in November 1982, and its adherents have been subject to surveillance and arrest.

Nevertheless, in February 1984 members of the proscribed Maitatsine sect struck again, this time in northeast Nigeria and in Yola, the capital of Gongola state. The army was again obliged to intervene, using artillery to quell the disturbances, but between 1980 and 1985 it was ill-equipment for riot control. As a result, more than 700 persons died, 30,000 were left homeless, and about 2,000 homes were destroyed and 1,500 damaged. In April 1985, riots inspired by Maitatsine adherents in Gombe claimed more than 100 lives and resulted in 146 arrests of suspected sect members.

Another violent incident occurred in November 1988 over the disputed succession of a new sultan of Sokoto. Ten persons died and fifty were arrested.

In 1987, in contrast to previously mentioned intra-Muslim disputes, religious conflict took onc3d on new and ominous dimensions when unprecedented violence between members of Nigeria's two largest faiths--Muslims and Christians--erupted at secondary schools and universities. Clashes between Muslim and Christian students in March 1987 at the College of Education in Kafanchan, Kaduna State, left at least twelve dead and several churches burned or damaged. The rioting spread to Zaria, Katsina, and Kano within a few days. Police reportedly arrested 360 in the city of Kaduna alone and about 400 in the university city of Zaria. Army troops again intervened, and the commander warned that the army would shoot anyone committing arson or murder. Bayero University in Kano was closed after about twenty students were injured in Muslim-Christian clashes. In Zaria Muslim students burned the chapel at the College of Advanced Studies and attacked Christian students the riots spilled over into the town, where more than fifty churches were burned. A curfew was imposed in Kaduna State, and outdoor processions and religious preaching were banned in Bauchi, Bendel, Benue, Borno, and Plateau states. All schools in Kaduna and five in Bauchi State closed. Babangida denounced these outbreaks as "masterminded by evil men . . . to subvert the Federal Military Government." He also issued a Civil Disturbances (Special Tribunal) Decree establishing a special judicial tribunal to identify, arrest, and try those responsible and banned preaching by religious organizations at all institutions of higher learning. In June and July 1987, Kaduna State authorities twice closed the exclusive Queen Amina College girls' high school in Zaria after clashes between Muslim and Christian students.

Relative calm prevailed among religious elements until January 1990, when thousands of Christians in the northern states of Plateau, Kaduna, Bauchi, and Gongola demonstrated against Babangida's cabinet reshuffle, which appeared to penalize Christian officers. Protesters of the Christian Association of Nigeria from all eleven northern states and the Abuja capital district marched on the Kaduna State government to protest the perceived religious imbalance and to present a petition signed by the top Roman Catholic clerics and the archbishop of Kaduna.

Data as of June 1991