A suicide bomber has killed at least 25 people and injured 63 of the 350 congregants after opening fire and then self-detonating at a Greek Orthodox church in Syria on Sunday.

More than 22 people were killed and another nearly 60 were injured when an Islamic State suicide bomber attacked a church in the Syrian capital of Damascus, officials said.

DAMASCUS (Reuters) -Syrian Christians were struggling on Monday to understand why their community was targeted in a suicide attack and whether they can rely on the Islamist-led government's assurances of protection.