Open Doors is asking for prayer for the Democratic Republic of Congo after at least 17 Christians were killed in a string of targeted attacks by Islamists.
Victims include two Anglican ministers who were killed in the first attack on 24 July.
This was followed by a deadly attack on two churches the next day. Seven churchgoers were killed when the buildings were set on fire.
The attacks took place in the Bogo area of eastern DRC between 24 July and 1 August.
They are believed to have been carried out by the Allied Democratic Forces (ADF), a militant group affiliated to the Islamic State that has a strong presence in the Bogo area.
The DRC is a majority-Christian country but the north-eastern provinces have been increasingly hit by jihadist violence.
Despite the government declaring a state of siege in the region last year, Open Doors warns that attacks on churches and communities have become "incessant".
Expressions of Christian faith have become "dangerous", the Christian advocacy group warns, with Christians being abducted or killed for wearing Christian symbols or meeting other believers.
"Now it is worse because it is targeting the church leaders," said Rev Besisa Birahure of the Anglican Church in Mugwanga, which was attacked by the ADF on 1 August.
"We are overwhelmed, what can we do? As things become harder may God sustain us to stand firm."
Rev Marcel Kisembo, Dean of the Anglican Cathedral in Boga, has counted 17 dead across the separate attacks.
Open Doors said that attacks against Christians, especially converts, are happening "with impunity".
"Pray for strength for the church leaders ministering under such difficult circumstances," it said.
"Pray for comfort for the bereaved, healing for the injured, release for the abducted and peace of heart for the entire church as they process their losses.
"Pray for wisdom for the authorities to take relevant measures to bring an end to this cycle of violence."