Easter's horrific bombings and loss of innocent life will severely test how well Sri Lanka and its leadership have moved to unite its diverse ethnic and religious communities since the widespread slaughter and isolation of (mostly innocent) Tamils after the Tamil Tigers' defeat 10 years ago.

Unhappily, the signs are that claims (faint though they have been) of improved unity in a country dominated by its Singhalese Buddhist majority (more than 70 per cent of the population) and its powerful Buddhist clergy, have barely masked fragile communal relations, long defined by prejudice, provocation and revenge.

Such sentiments were, during the so-called civil war with the Hindu Tamil Tigers, viciously exploited to provoke, for political gain and to isolate religious minorities, fear and retribution across Hindu, Muslim and Buddhist communities. The Singhalese Buddhist's stranglehold tightened and led to the rise of the corrupt president Mahinda Rajapaksa and cronies; cronies now headed by his successor, President Marthripala Sirisena, who recently attempted to install Rajapaksa as Prime Minister by executive decree - and the Constitution be damned.

Since the British left in 1948, Sri Lanka's small Christian community (about seven per cent of 21 million) survived more or less unscathed and was not targeted. They had comparative immunity from the pain of the Buddhists, Muslims and Hindus, though in contemporary times they, as fellow Sri Lankans, rallied behind their wounded compatriots.

Their community's solidarity had derived from a mixing, over the centuries, of Singhalese with the Christian Dutch, Portuguese and, predominantly, British colonisers. This made them less than Singhalese, acquiring the ethnic description of 'Burgher' - which, though Portuguese catholic in origin, was loosely applied to all mixed Euro-Sri Lankans. Less enough that, in the 1960s, the world's first woman Prime Minister, Sirimavo Banadaranaike, nationalised their exclusive preserve of the highly successful tea production. This boosted her standing and provoked Burgher Christian migration. But since then they have kept out and been mostly left out of Sri Lanka's murderous troubles.

During our time there my wife and I were close enough to the unrelenting death and destruction to attract threats. Once, on the advice of British Intelligence, the Sri Lankans posted heavily armed guards on our residence.

The attacks on Christians this Easter are not as easy to fathom as past attacks against Tamils and Muslims. If, as the government was quick to claim, the source is exclusively domestic and Muslim, the obvious questions are: how could an apparently sophisticated organisation materialise, under the noses of what was a sharp security apparatus, with the skills, materials and resources for a huge, complex operation; and what advantage would any domestic interests gain from attacking Christians?

Unless there is an underlying and (characteristically) devious intention, domestically, to revive public hostility against Sri Lanka's Muslims (just under 10 percent of the population) to provoke the same kind of "spontaneous" retribution against innocent Muslims which enlivened earlier governments.

It is more likely the attacks will prove to have been directed and resourced, wholly or in part, by external Muslim extremists, to create another instance, suitably remote internationally, of attacks on peaceful Muslim communities - to inspire an international redoubling of the struggle against the enemies of Islam. After the defeat of the ISIS-inspired caliphate, this would be consistent with the move of extremists from ground to cyber forces and the reappearance after five years of ISIS's Abu Bakr al-Baghdadi. The growing world of Muslim extremism could then add Sri Lanka to its successes - such as the US-led invasions of Afghanistan and Iraq, and the catastrophic US-led support for unprepared minority political and militia entities in Syria and Libya.

After the Sri Lanka attacks, Prime Minister's Scott Morrison's well-deserved praise of new Australians (Sri Lankans in this instance) who, through bitter experience, so value our freedoms, is at stark odds with the election-time trumpeting of his populist capping of Australia's miserably low refugee intake.