Christians are being called to pray for their fellow believers living in persecution hotspots after Sunday's bomb attack on an Indonesian cathedral. 

Sunday's blast in Makassar injured 20 worshippers as they were leaving a Palm Sunday service held at the start of Holy Week. 

The two suspects, a newlywed couple said to be in their 20s, are believed to be members of the Islamic State-affiliated Jemaah Anshorut Daulah (JAD), a radical group that has been linked with other bomb attacks in Indonesia.

The attackers detonated a pressure-cooker bomb at the gates of the cathedral when they were challenged by security guard. The suspects were the only fatalities.

Release International is asking people to pray as Christians prepare to celebrate Easter this weekend, a time of year that, along with Christmas, has been "favoured" by terrorists, it says. 

"Please pray for Christians in trouble spots around the world," said Release International CEO Paul Robinson.

"Pray for God's protection and that Christians will continue to be courageous and faithful in their witness.

"The message we hear time and again from our partners around the world who are persecuted is that their faith is worth it. Persecution reminds us why we are living. It teaches us to use the freedoms we so often take for granted to the full.

"Living out our faith courageously is the biggest lesson we can learn from our brothers and sisters who are patiently suffering for their own faith worldwide.

"Pray also that grace will abound, and they will remain faithful to Jesus' call to overturn hatred by loving their enemies." 

Indonesia is the largest Muslim-majority country in the world, where the population is 87% Muslim, followed by Protestants (7%) and Catholics (3%). The rest are Hindus, Buddhists and other minority faiths. 

Indonesian church leader Ari Hartono, a local partner of Open Doors UK & Ireland, said extremists are trying to divide the different faiths in Indonesia. 

"They are especially trying to sow division, especially between Christians and Muslims at a strategic time," he said.

"We are approaching Easter this week and Ramadan begins the following week. They are not succeeding; the five faiths on this island are standing strong together."

He added, "Our church leaders have issued a joint statement with other faith leaders to the Indonesian people saying this has not come from our faiths and we will not let it sow discord and chaos. All five faiths will be standing together."

Christians have been targeted by Islamist extremists in recent years, with four Christians murdered in Sigi four months ago, and 30 killed in a church suicide attack in 2018. 

"After the 2018 attacks the terrorists changed strategy and focused on police stations and government buildings. Now they have reverted to attacking our churches," said Mr Hartono.

Benedict Rogers, Senior Analyst for East Asia at Christian Solidarity Worldwide, urged the Indonesian authorities to put a stop to terrorism. 

"From these attacks, it is clear that the religious intolerance we witnessed in 2018 has yet to be fully addressed, and that the JAD remain a serious threat," he said.

"We therefore call on the Indonesian authorities to ensure a swift and thorough investigation into the attacks, ensuring that all those involved are brought to justice, and that such events are never repeated."

Another Open Doors partner in Indonesia, Brother Sam (whose name has been changed for security reasons),  has warned of an increasingly hostile climate for Christians. 

"The situation for Christians has been deteriorating in recent years, with Indonesian society taking on a more conservative Islamic character," he said.

"Christians who grew up in a Muslim home often experience persecution from their families."

Mr Hartono stressed, however, that Christians will not be discouraged from celebrating Easter, despite the heightened threat, and that they bear no ill will towards other faiths or even their attackers.

"We have a love for our enemy. This is not coming from our fellow Muslim. It is always in our mind how to love them," he said.