Why is it that Christian (especially Catholic) doctrine espouses the idea that we're born sinners, rather than born pure? Wouldn't it make more sense to tell people that normal society is a temptation to lead you away from your childhood purity, and that only Christianity can maintain this purity? Rather than telling everyone that everything is evil, and only through Christianity will you be saved.
Cos with the latter, I would find it incredibly tempting to just stay as I was born. I was born a sinner, immoral society only keeps me in this state and doesn't extend it and it takes effort to gain something which I'm not sure I want. If I were told that I was born pure though, I would want to just maintain that, and to avoid things which would degrade it.
It would also have no pyschological drawbacks, as any "sin" attributed to you would be directly through your own choices.