(CNN) The bombings on Easter Sunday of eight sites in Sri Lanka, including three churches, seemed designed not only to inflict mass casualties but also to send a message.

Initial investigations showed the chain of bombings was carried out by "a radical Islam group," perhaps as retaliation for mass shootings in March at two mosques in Christchurch, New Zealand, Sri Lanka's state defense minister, Ruwan Wijewardana, said Tuesday.

ISIS has reportedly taken credit for the slaughter in Sri Lanka but did not immediately offer proof of its involvement.

To some, the bombings, carried out on the holiest day in the Christian calendar, has fed a narrative of religious war. Christians and Muslims, this theory goes, are increasingly at odds and willing to strike at each other's spiritual hearts -- sanctuaries.

To be utterly clear: Any attack on any house of worship is heinous and should be unequivocally condemned. In too many parts of the world, Christians are attacked by Muslims and vice versa.

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