ABUJA, Nigeria — Isa Salisu ran almost a mile without stopping in a bid to escape his attackers at a military checkpoint in Jos, a large city in north-central Nigeria.

“Three of us were returning from the cattle market,” said Mr. Salisu, a 20-year-old herder, recalling how he and two friends were driving 150 miles from the city of Bukuru to their home in Barkin Ladi, closer to the national capital of Abuja. “Our vehicle was ambushed.”

Knife-wielding youths belonging to the Berom, a Christian ethnic group of farmers, attacked Mr. Salisu’s car. He was eventually able to escape, but his companions were not so lucky. They were hacked to death.

The reason for the ambush: Mr. Salisu and his friends were Muslim members of the Fulani ethnic group who mostly raise cattle. They were caught in a place and time of particularly tense relations between Nigeria’s Christian and Muslim populations.

The attack was just another incident in a budding religious war that many fear could grow far worse than the conflict against Boko Haram, the Islamic State-affiliated terrorist group that rampaged across the country’s remote north for almost a decade until Nigerian forces launched a serious campaign against them two years ago.

The Boko Haram reign of terror in large part has reignited Nigeria’s religious wars.

The Boko Haram insurgency pushed herders out of traditional grazing lands and into farming regions to the south. That in turn set off a fierce competition for land and resources.

Conflicts between mostly ethnic Fulani Muslim herders and predominantly Christian farming groups such as Berom have claimed 3,000 lives in north and north-central Nigeria, according to government statistics.

In April, the U.S. Agency for International Development organized a three-day conference in Abuja for officials, herders and farmers, as well as religious and ethnic leaders, to try to hash out their differences. Among the problems identified in the discussions: a proliferation of arms, diminishing farmland and grazing pastures resulting from climate change, and incendiary media coverage of religious clashes.

But the country’s leading religious figures are showing little effort to reconcile the two communities. This month, leaders of the Christian and Muslim communities debated over which was the more persecuted.

Catholic Bishop Matthew Kukah said Christians are effectively shut out of practicing their religion in Muslim-majority regions. “Up until today, you can’t find a single governor in northern Nigeria that will effortlessly sign a certificate of occupancy for the building of a church — nowhere,” he told reporters.

That led the Nigerian Supreme Council for Islamic Affairs to issue a statement accusing the bishop of trying to “play the underdog in highlighting their pathological hatred and undisguised intolerance for Muslims in this country.”

“Without any fear of contradiction whatsoever, the [irrefutable] truth is that no religious group faces the persecution that Muslims face in Nigeria,” the council said. “From the usual hijab saga to religious witch-hunting in private and public establishments, Muslims have always been subjected to the same treatment the colonial masters made them to suffer.”

Pressure to act

As with the Boko Haram menace, the government of President Muhammadu Buhari has been criticized for acting slowly to address and quell the carnage.

“There are various factors responsible for these conflicts, but mostly it’s due to the inability of government to take decisive action,” said Nurudeen Kyaagba, a researcher with the Kaduna-based African Research and Development Agency. The think tank is seeking to find lasting solutions to conflicts between farmers and herders in the West African country, the most populous on the continent.

The latest large-scale violence occurred in June when a group of Fulani attacked Gashish, a Berom community. About 300 were killed. Barely able to escape to safety, Francis Chong, president of the Gashish Youth Development Association, said his two brothers died in the violence. “The herdsmen took positions, surrounding the entire villages,” he said.

Berom youths responded by blockading sections of the busy Jos-Abuja expressway to avenge the deaths of their kinsmen. They attacked commuters identified as Muslims.

The Nigerian government signed a protocol with the Economic Community of West African States for the free movement of people. It allows herders from 15 countries in the region to cross one another’s borders or relocate within their respective countries.

But Mr. Chong said Mr. Buhari and other officials have done little to smooth relations between newcomers and those already on the land.

For Comrade Peter Ahemba, the conflict started when the local legislature enacted a law against open grazing, barring herdsmen from locating anywhere they please. The herdsmen responded by assaulting farmers on their own land.

Mr. Ahemba is president of the Tiv Youth Organization, an umbrella body for youths of the Tiv, an ethnic group of Christian farmers from Nasarawa.

“This crisis, aside from the killings and loss of lives, affected our economic activities,” said Mr. Ahemba. “Our people have not been able to access their farms because of the destruction of houses and the fear that is still prevailing.”

The U.N. Security Council has issued a statement condemning the conflict and calling for action.

“These attacks have had a devastating humanitarian impact including through the displacement of a large number of civilians in Nigeria, Cameroon and Chad, and represent a threat to the stability and peace of West and Central Africa,” the statement said.

Alhaji Muhammed Hussaini, local leader of a Fulani herder’s welfare group, the Miyetti Allah Cattle Breeders Association of Nigeria, agreed that the government needs to act. Christians have been stealing his members’ cattle, he said, and the Fulani have no recourse but to take matters into their own hands.

“Injustice is the major cause of this lingering crisis,” said Mr. Hussaini. “Certain criminal elements both within the Fulani and natives who connive to rustle cows. Once a Fulani man loses his cows, he knows no peace because for him cattle is only means of livelihood.”

He said the Fulani community has lost more than 500 kinsmen since 2012 and more than 20,000 cows to rustlers.

Mr. Salisu said he fears that the conflict could escalate from arguments over land to a full-blown West African religious war.

“I can’t see myself return home now,” said Mr. Salisu, who escaped with a knife wound to his chest and now lives with relatives in Jos. “I can go back to Barkin Ladi only if our security is guaranteed.”