Being a sinner just for being born

[robvalue]

Ignorant: Thank you for your answers

Of course, I care about the wellbeing of others. That is the basis for my morality. But I don't do it because of the consequences to me "if I sin". I do it because I want to. I could get away with doing lots of "sinful" stuff, but I don't.

What I don't understand is the need to introduce "sin" as a separate concept.

I'm still not quite understanding how it works. Are we judging each other's actions as being sinful or otherwise? So it's just another way of saying we think an action is immoral? Or extremely immoral? Is god's opinion of importance here, and if so, why?