My boy,first of all there is absolutely no comparison to ISIS. Absolutely no comparison. If there's anything comparable to ISIS in this conflict,that's the thousands of mujahedeen who volunteered to fight in the ArBiH. And indeed,many of them would later become AQ members,some leading members and others would fight on the radical islamist side in other wars.
As for the Greek Volunteer Guard,there is no evidence at all that they took part in any atrocities. Even those who have accused them or implied that they did,provided no evidence,no proof of anything like that and the cases were dropped. Even when some dared to take them to court,not only did they present nothing,but the accusers didn't show up
Now tell me,are you some kid? Or simply uneducated of history? Because you're trying to discard historical sources and testimonies from 1453 by simply saying "ah,Serbs are evil,Serbs are Orthodox,so all Orthodox are evil,liars and all sources are probably fabricated".
That's just a childish,idiotic conclusion. In the same way I could say: "Ah,Ottomans killed people,Ottomans were Muslim,all Muslims are evil and unreliable".
Does that make any sense?