It's not a lie of you believe it - George Constanza
It is one of the problems with religion. Belief makes all things possible. Even lies. Most religions are steeped in lies and belief makes it OK to hold onto them and cherish them and even fight for them. All religions. Mine too by the way. Let's not quibble. We just try to separate fact and fiction for what they are. And the facts are often murky, requiring a webbing of intricate lies and false assumptions to support them.
But this was about sin. I've come to think that sins are those things that bad about having done. And this changes over time, What we did once, and might have felt good about, can become an embarrassment or feel like a mistake hours, days, weeks, or years later. There are also things that we feel forced to do that we might not feel good about. And there are things that happen to us, that we might feel, in hindsight, that we had some hand in their happening. There are probably more aspects to this than I can write in this short blog.
Maybe this confuses guilt and sin. Maybe they are one in the same. I'm going to cogitate this a little more.