At least 38 people have been killed since Christmas Eve in attacks across Nigeria, including assaults against two churches.
Local police suspect radical Muslim group Boko Haram, which has a history of anti-Christian violence, in the church attacks.
In the northern town of Maiduguri, armed men dragged the pastor of Victory Baptist Church out of his home and then shot him to death. Two men rehearsing for the carol service at the church and two people walking nearby were also killed. Afterwards, the mob set the church and pastor's house on fire, according to The Associated Press.
Also within the same city and on the same day, another group of men attacked the Church of Christ in Nigeria and killed an elderly security guard.
Adding to the death toll are bomb blasts Friday evening in central Nigeria that killed 32 people. Two bombs exploded near a market where people were Christmas shopping, another exploded in a predominantly Christian area in Jos, and a fourth bomb blasted near a road leading to a mosque.
It is currently unclear if the church attacks and the bombing in central Nigeria are linked.
Nigeria, which is nearly evenly split between a mainly Muslim north and a predominantly Christian south, has a long and bloody history of sectarian violence. Most of the conflicts occur along the central region where Muslims and Christians fight moreso over grazing land and ethnic lines than over religious differences.
Earlier this year, more than 500 people died in a sectarian conflict in Jos and surrounding area. Although it was initially reported as a Muslim-Christian clash, local church leaders later clarified that it was more about social and economic factors than religion.
Authorities arrested hundreds of people suspected to be linked to the Jos massacre. But in September, more than 100 members of Boko Haram escaped jail following a violent raid of the prison in the northern city of Bauchi.
Boko Haram members have killed dozens of Christians, as well as police and local leaders. The Nigerian government has tried to crush the group, destroying its mosque and arresting its leader, but it appears to be reviving.
Nigerian President Goodluck Jonathan, a Christian from the south, vows that the government will "go to the root" of the recent Christmas Eve attacks.
"We must unearth what caused it and those behind it must be brought to book," said Jonathan.