Plato on Original Sin and the Source of Truth

Throughout the last several millennia of history, when the big questions of life that philosophy seeks to answer come up, perhaps the first name to be brought in as an answer is that of Plato; while Plato can have some good answers, there are foundational problems with his views that manifest themselves when scrutinized closely. Therefore I hold that Plato’s worldview is fundamentally flawed when compared to that of Christianity on the topics of the nature of man and the source of truth. I will seek to unearth some of the discrepancies in Plato’s philosophy by examining the following questions: what is a human being and why is it possible to know anything.
First I will examine the views of Plato concerning the question, what is a human being. What does it mean to say the “essential nature” of man? We often try to be something that we’re not or disguise ourselves to appear differently than we would appear normally; I will define the “essential nature” of man to be what man is at his core when all our deception is stripped away.   This is how man would appear to a perfectly omniscient, impartial judge.   With this definition in hand, we can seek to discover how Plato would answer the question, what is the essential nature of man?
Though Socrates seems to be rather guarded in how much of his own opinion he gives away and always asks for the opinions of those around him without volunteering his own, Plato tips us off to what he believes with statements like the following:
Socrates:   Well now, a man who has learnt about carpentry is a carpenter, isn’t he?
Gorgias: Yes.
Socrates: And a man who has learnt music a musician?
Gorgias: Yes.
Socrates: And a man who has learnt medicine a doctor, and so on. In fact a man who has   learnt any subject possesses the character which knowledge of that subject confers.
Gorgias: Of course.
Socrates: Then by the same reckoning a man who has learnt about right will be righteous?
Gorgias: Unquestionably.
Gorgias pg 24 section...