<P> Twelve out of Nigeria's thirty - six states have Sunni Islam as the dominant religion . In 1999, those states chose to have Sharia courts as well as Customary courts . A Sharia court may treat blasphemy as deserving of several punishments up to, and including, execution . In many predominantly Muslim states, conversion from Islam to another religion is illegal and often a capital offence . </P> <P> According to a Nigerian study on demographics and religion, Muslims make up 50.5% of the population . Muslims mainly live in the north of the country; the majority of the Nigerian Muslims are Sunnis . Christians are the second - largest religious group and make up 48.2% of the population . They predominate in the central and southern part of the country . </P> <P> For reasons of avoiding political controversy, questions of religion were forgone in the 2006 Nigerian census . </P> <P> Boko Haram conducted its operations more or less peacefully during the first seven years of its existence . That changed in 2009 when the Nigerian government launched an investigation into the group's activities following reports that its members were arming themselves . Prior to that the government reportedly repeatedly ignored warnings about the increasingly militant character of the organisation, including that of a military officer . </P>

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