the reason why Plato and Aristotle, Socrates and other philosophers had a basis to believe that there even was such a thing as good and evil, was because they borrowed the Christian/Old Testament presupposition that there was such a thing as good and evil

Yes, you've asserted that several times but we are still awaiting any sort of evidence that it wasn't from any of the other contacts the Greeks had or - perish the thought - something they developed themselves? But I suppose you would declare that to be really christian as well. Oddly enough, you seem happy to call everyone as essentially Christian who says the aren't, except for those people who think they are ...