The main problem with the idea of sin is that it contradicts the existence of an omnipotent, omniscient, omnipresent and timeless deity. You can have one or the other, but both at the same time is a paradox.
Let me explain why.
There are many versions of sin, depending on religion, custom, culture, etc. But the main gist is that sin is something that is a transgression against god—something that goes against his will.
The problem is that if god is omnipotent, omniscient, omnipresent and timeless, everything that exists, exists precisely the way it is, precisely because god wanted it to exist that way. If god willed everything into existence exactly the way it is, then nothing within this willed universe can be said to go against the timelessly omniscient will that created it.
And if something god willed into existence happened to go against his will later on, this would be an internal conflict within an omniscient mind that can’t decides what it wants. Even if such a thing were possible, how could the responsibility for it fall on anyone other than the conflicted mind that created everything?
As for the common religious excuse about human free will being responsible for sin, if god granted humans free will, knowing full well (by means of his timeless omniscience) that they would sin, then it cannot be said that god didn’t knowingly create sin. He just deliberately created it through humans, knowing in advance what would happen. This escapes neither god’s plan nor his deliberate, knowledgeable doing.
To say that something can go against the will of an omnipotent, omniscient, omnipresent and timeless creator is the same as claiming that something in a novel can go against the will of the novelist. Sure, the novelist could write some stuff he didn’t like or that he regretted later, but it’s still his will that made him put it in the story. It would make no sense for the novelist to blame a character he created for going against his will.
Even if god purposely put something into the story that he wasn’t sure about or didn’t like, it’s he who decided to put it in there. It’s still a result of his own will. If he didn’t want it, it wouldn’t have existed in the first place.
I’m not making up any of these claims about god being omnipotent, omniscient, timeless and omnipresent. This is what’s in the religious stories, not in mine. I’m just pointing out that the story itself makes no sense because it contradicts itself on its own terms.
Get the Debating Religion book now and start debunking common religious arguments in real time. This is a practical hand-book comprised of short segments that introduce common religious arguments followed by bullet-point replies that debunk them—simply, quickly, straight to the point.