I don't think it's unrealistic at all. There are people in isolated areas --- think deepest Appalachia --- who never interact in any meaningful way with anyone who is "different" from them, might only have been to the nearest reasonably good-sized city a few times in their lives (for medical care, possibly a school field trip, etc.), and whose life revolves around whatever little town, county, or school district they happen to live in. Their only knowledge of Catholicism comes from distorted snippets on TV, and random concepts of Catholics being people who drink too much (these people approach alcohol the way faithful Catholics approach sɛҳuąƖ sin), sodomite priests who abuse children, and superstitious immigrants and their descendants who fall down and worship statues of Mary as though she is a goddess. It is possible that they've stumbled upon a Jack Chick comic book here and there. Their little church, their little town, and their family and friends are all they know. A tiny minority of them even handle poisonous snakes. (I don't care what anyone says, a person who takes a venomous snake in their hands and drinks strychnine is nothing if not sincere. They're not doing it for show.)
LT is right, it is totally and completely unrealistic, I will go so far as to say it's impossible, or all but impossible. Original sin is washed away, but our inclination to sin, our tendency to do evil remains with us our whole life.
What you are suggesting is rooted in Liberalism, more specifically, Naturalism.
As explained in this snip from a sermon given by Fr. Wathen:
"They [the bishops] are going to have to recognize that liberalism is intrinsically false and will not work, because beneath liberalism, the philosophical basis of liberalism, is what we call Naturalism.
Naturalism proclaims, among other heresies, that there is no such thing as original sin, that man is basically good, that he means well and if you let him grow up, he’ll grow up good, he’ll grow up moral, he’ll grow up to be a good fellow. But Catholic doctrine says that man is not basically good, that he comes into the world bent on evil and if you leave him to himself, he’ll become a savage, he’ll become amoral. He’ll not only do most wicked things but he will try to justify them.
We have to recognize that this is the error of liberalism, that it wants to treat all men as if they really are not bad and that the only reason they are bad is that they are misguided, that they’re victims of circuмstances and of their environment. That they are bad because their mother, or their father, or their parents mistreated them, or because they were deprived of something, or because they didn’t get a chance to go to school with white folk, and all that kind of thing. And we say that no, a man is bad because of original sin and he doesn’t mind being bad, he chooses to be bad. In other words, he cannot blame his wickedness on Adam only, because with every day that passes, he confirms the evil within himself.
At the second Vatican council they tried to say that; "men are bad, that men are anti-Catholic, because the Church has not treated men correctly, and if the Church approached them kindly, and with understanding and you might say with intelligence, modern public relations - they would have come into the Church instead of opposing it and being against us in every way and distrusting it and even engaging in efforts to destroy it".
And the bishops are going to have to recognize that original sin is operative in every soul and it always will be, and that all men have to be disciplined, they have to acknowledge that by themselves they will do wicked things. And Almighty God in the Church established an authority over them, and they may not like to be told what to do, but they must be told what to do, and they must be warned of the consequences of not doing it, and the consequences ultimately are hell fire..."