Boko Haram, which wants to impose Islamic sharia law in Nigeria, said yesterday's attacks in the cities of Zaria and Kaduna were retaliation on Christians for destroying mosques and, according to the group, turning others into "beer parlour and prostitution joints."
"Let them know that now it's the time for revenge God willing," the group said in a statement.
"From now on, they either follow the right religion or there will be no peace for them."
Government and Red Cross figures on the death toll in yesterday's attacks differed. The Red Cross said the at least 52 people were killed and 131 others wounded in the attacks.
Analysts say Boko Haram is trying to trigger clashes between Christians and Muslims in the country which is equally divided between the two faiths.
The series of attacks began when a suicide bomber drove at high speed through a barricade at the EWCA Goodnews Wusasa Zaria church early morning.
A Kaduna state official, who asked to remain anonymous because he was not authorised to speak to the media, said that blast killed at least 24 people and injured 125.
The Nigerian Red Cross Society, however, reported that two people died and 22 were injured in the attack.
Within minutes, another explosion occurred at the Christ the King Catholic Church in Zaria, according to Nigeria's National Emergency Management Agency. (more)