Ok... so all those philosophers in greek academies, what were they arguing about and trying to discover if not the truth?

Why was their a word for truth if they had no concept of it before christianity?

Why does truth in english have a germanic root? If europeans had no concept of a single truth before christianity then the concept would have been introduced to the language via latin missionaries and we've be calling it "vera" or something.

Why are indo-european religions like zoroastrianism based around the idea of a single truth?