Any credible source that immigration, illegal or legal, is largely responsible for the rise of Neo-Nazi criminal activities? The fact that far-right extremists try to turn poor people against each other, by dividing society along ethnic and religious lines does not necessarily mean that immigration is what led to the increase of their political influence. Even in France, Le Pen received most of her support from the communities with the least contact with immigrants. In fact, immigration to Greece has dramatically declined since the mid-2000s, when the situation in Eastern Europe gradually stabilized. In 2012, the year of the great growth of the Golden Dawn is marked by the lowest percentage of immigration flow, according to the data of the Organisation of Economic Cooperation and Development.
The same applies for crime statistics, as the reports of the police indicate:
I guess immigration numbers changed due to the refugee crisis, but funnily enough, the power of the Neo-Nazis stagnated, so I think we can safely rule out immigration, the most common scapegoat of the far-right, as at least a determining factor for the emergence of Neo-Nazi terrorism and activism. The same conclusion is true for the claim that family men turn into Nazi sociopaths, because they are scared about Communism. The percentage of the Communist Party of Greece, which indeed has a history of liquidating Nazis and their collaborators, during WWII and the subsequent Civil War, has remained the same. Even in what concerns post-WWI Germany, this excuse is basically a myth. The only contribution of Communism to the rise of Nazism was by encouraging the German elites to endorse Hitler and his ideology, in order to use them as a deterrent against labour movement and the Communist Party. Personally, I would blame Krupp rather than Stalin for that, but each on his own. On the other hand, modern Greece and Germany of the '30s share the common element of experiencing a severe financial crisis that crippled a fragile and politically immature lower middle-class.