A homogenous nation has respect and pride in its shared culture, shared religion, shared history.
Once you get influxes of third worldlers into a country you can almost guarantee they will be the ones commiting such crimes. Or drug addicts are the only other possible suspects.
Where I come from, we have folks from every race, continent, color and creed, yet, on the whole, life is pretty peaceful and quiet. OTOH, criminality knows no boundaries or ethnicities - for example, during the days of Prohibition, there was hardly an ethnicity which did not have its version of a Mafia or other criminal element. Does this mean that the Italians, Irish, Jews, Poles, Greeks, etc, as a whole, should be regarded as renegades and suspect? In more recent times, there have been Japanese, Chinese and Vietnamese who, by their criminal activities, have sullied the good name of their hard-working and honest compatriots, who are in the vast majority to the criminal element. The same goes for "established" Anglo-Celts: there are all too many of their names among the ranks of the criminals.
It would be most instructive to get a breakdown of the ethnic background and circumstance of those who are looting churches in Greece. I have many friends who are Greek, as well as folks in my extended family of the same ancestry. None who have visited the country in the past 25 years have had much to say that is good. If anything, they are scathing in their assessment of their fellow Greeks, including members of their own families, who have, all too often, put their own self-interest above the generosity of those who have benefited them over decades. Self-centredness, greed, selfishness, an inflated sense of their own worth, institutionalized corruption, an almost cultural desire to milk "the system" for all they can get ...
I can only conclude that Greece's current misfortunes are, to an overwhelming degree, self-inflicted. The chickens have indeed come home to roost. That's why they're all screaming now.