https://en.wikipedia.org/wiki/Sin
In a religious context, sin is the act of violating God's will. Sin can also be viewed as any thought or action that endangers the ideal relationship between an individual and God; or as any diversion from the perceived ideal order for human living. To sin has been defined as "to miss the mark".
We are all sinners by the mere fact we are born. Since Adam and Eve rebelled against God, they "missed the mark" of perfection. They were now imperfect. Hence, just as a dented cake tin cannot produce a perfect cake , so too man cannot produce a "perfect" man.
Whether you are an atheist or a believer, you are still born in sin.
This is where organised religions are guilty. They have introduced the idea that when a person does anything wrong - it is a sin. No it is not!!
As to innocent children. Not all children are innocent - sad to say. When young children as young as 8, 9 or 10 can go out and kill, even "rape" are not innocent and in many cases, religion has nothing to do with it. It is the environment they live in.
So no Naomi - you "do not hit the nail" on the head - you have absolutely no idea and are just plucking ideas out of the air.
As to going to various churches, you poor dear!! you must be so confused as from my experience none of them speak in unity!!