I recently read the stories of Damaskinos of Athens, Chrystostomos of Zakynthos, Ioachim of Volos and others. All were bishops and all had everything to lose by helping the Jews, be it their own personal safety or that of their church and flock. Further, it seems like they were much further up the church hierarchy than the priests who helped the Jews in Poland, France and elsewhere.
Well, the archbishop stated that they were all Greeks. As such, they took care of their own.
Besides that, the Orthodox Church has taught that all people are the children of God and have an inherent value. So by doing what could be done for the Jews the clergy exemplified the sort of behavior expected out of all of us. It is worthwhile to note that the people also did what they could.
Of particular note is that Mount Athos even hid jewish women and children within their lands. This was huge for them but they did it without hesitation as it was the right thing to do.
Or it could be a classic case of someone telling a Greek what to do. The answer is always going to be no.
Before I forget, I had the opportunity to help an american student who no idea that his grandmother came from greece connect with his family. His grandmother thought that all of her family had died in the holocaust and they thought that she had died. She had been put on a ship as a little girl and sent to America while the rest of the family was split up and hidden by Orthodox families in their region. That is how they survived the war. Simply amazing.
Even more amazing was that she was able to speak with her siblings for the first time since the war. Just amazing.
Edit: Archbishop Iakovos of America also marched with MLK.
Are there any good books about this in English?