retrospect is always 20/20. meaning if we knew the result of all our actions we would be far more intentional. Perhaps if the "bad guy" knew that he was saving the kid he wouldn't throw the brick to begin with. We do not know the results of our actions and our actions that we end up doing ony reflect our current knowledge not the end result.
It is the condition of our heart where the evil begins, the action just reflects that condition. If we intended to do evil but good happens instead all this shows us is we do not have control over all things but it does not discredit the sin that took place in our heart.
Sin is a focus that cannot come from God because he is without sin. Since God created us, and he is without sin, he would not have created us with a "intrinsic ability to create evil". Sin then is something that has a source outside of God and outside of us. Sin has a constant re-birth in our lives, which is the sinful nature, not because it is a perpetual motion machine spawned inside of us but because of a source that pushes this focus on us. This source is Satan.
Satan also has been created by God, as all things are, but this does not mean God created Satan with sin. Satan is not human and is not dictated by the design of humans. We approach things very differently and the concept of disobedience to God with Satan is a lot different than our own concept and ability to sin for humans. I do not fully understand the law that Satan is govern by because I am not under his design but I do know we cannot apply our rules with Satan because we are not under the same system. I can use my knowledge from my own system to know that sin does not come from me and know it does not come from God so the sin that I am a part of is from an outside source.
are you suggesting you, as a human, cannot sin? I probably arrived at the wrong conclusion, but that's what the latter part of your post seems to imply.
I agree though that god can be seen as without sin. I've heard some pretty desperate, silly theorys to try and explain how god could create satan or sin. Free agency comes to mind as being one of those theories. I don't put much stock in them, especially that one, as much of a brain-picker as it might be.
To separate god from sin seems to repeatedly lead towards the idea of free will, which is am a strong believer am. Actually, i think it's that very idea that gives such value to the idea of gods omnipotence. To say it's either or, seems to restrict god, rather than understand him.
but back to the original post...
I think intention has a role in whether or not we are sinning. To be open to what it is that god wants for us, listening to the holy spirit. Above all else, reading his word helps provide us with an idea of how we should act in this world.
Words like evil and good are abused, and in the secular world, reduced to things that cause us pain, or on some level discomfort. These are incorrect definitions of evil, and so, and have nothing to do with sin.
True, even our smallest actions can cause a ripple effect, like out in some great big pond. That's one reason why i've never understood why people ask for blessing from god. For what might seem like a blessing one day, might turn out to be trouble the next.