Reuters reports that clashes between Nigerian Christians and Muslims have already killed hundreds of people this year alone.
But although the violence is the worst between members of the two faiths since the Bosnian war of 1992-1995, the root causes go far beyond religion, the group's report said.
Corruption, mismanagement, land disputes and the lack of aid for victims or punishment for troublemakers have all fuelled tensions, especially in the "Middle Belt", where the mostly Muslim north meets the largely Christian south, it said.
Attacks by radical Islamist groups such as Boko Haram that exploited these secular issues and revenge killings by Christian and Muslim gangs have reinforced the religious aspect of the violence.
"There is a possibility that the current tension and conflict might become subsumed by its religious dimension (especially along geographical 'religious fault-lines')," the report said, warning that blaming only religion for the strife would make that incomplete view "a self-fulfilling prediction".
The 12-member joint delegation was led by World Council of Churches (WCC) General Secretary Olav Fyske Tveit of Norway and Jordanian Prince Ghazi bin Muhammad, chairman of the board of the Royal Aal al-Bayt Institute for Islamic Thought.
The report identified dozens of separate problems whose resolution could contribute to overall peace.
The wealth gap between the oil-producing states in the south and the resource-poor north was a leading factor in regional tensions, as were land disputes such as the lack of recognised grazing land for nomadic Fulani cattle herders.
Indigenous inhabitants in many Nigerian states enjoy more legal rights than "settlers," who have no access to free healthcare, education, land and jobs even though some of them moved into those areas generations ago.
"It is an enormous problem that needs to be solved or resolved at the federal and constitution levels, perhaps with a constitutional clarification or amendment," the report said.
It also said tensions arose because Goodluck Jonathan, a Christian southerner, served out the presidential term of northern Muslim Umare Yar'Adua after the latter's death in 2010, then won election in 2011.
Some Northerners say this broke a power-sharing agreement between north and south.
But the report did say that religion itself had played a part in fuelling the violence.
"In Nigeria, three things are intertwined - religion, politics and ethnicity - and the three are beclouded with corruption, poverty and insecurity," the report quoted former justice minister Prince Bola Ajibola, one of several Nigerian officials who accompanied the delegation, as saying.