I've been debating on the issue of sinful nature. I know the textbook Christian position is that man inherits the sinful nature from Adam and Eve, who acquired it as a result of the Fall.
Because of this nature, generations after generations of humans commit mishaps and atrocities of all kinds. Since some Christians (perhaps most) say that the eating of the forbidden fruit was a sin, I wonder how Adam and Eve, in their pristine condition, could have committed this very first sin of mankind in the absence of the sinful nature. To have them sin would have been a Catch-22 situation. They couldn't have sinned without the sinful nature, yet they couldn't have acquired it if they hadn't committed the first sin.
Right now I've been assuming that eating the forbidden fruit was a sin. Of course if we deny its sinhood, we wouldn't face the above-mentioned dilemma. I've seen Christians insist that it was a sin, and their position commits them to the view that there are two types of sin. One does not require sinful nature, and the other does.
Their story, or put it more politely, theory, is undesirable from the perspective of Occam's Razor. They'd need to recognize two subcategories of sin, and the possibility that modern humans can commit sins without sinful nature, just as Adam and Eve did. However, it is a priori convincing to adopt a theory with fewer theoretical entities. This is not say that their story is absolutely wrong, but that it is to be adopted only if evidence can be produced in its favor.
A simpler, thus a priori more convincing, alternative is to claim that Adam and Eve were created with sinful nature, and they committed the first sin with sinful nature, just as we all do. With the two competing theories at hand, the burden of proof lies with the one that is more complicated, i.e. the one that assumes two types of sin.
For Christians assuming the more complicated theory, my question is: where in the Bible does it say that Adam and Even were created without sinful nature?
For Christians who consider the eating of the fruit as anything but a sin, my question is: who created the sinful nature? Some Christians say it spontaneously arose in Adam and Eve after the Fall, reluctant to acknowledge God as its maker. But this cop-out merely paraphrases 'who created the sinful nature' as another question: who invented the mechanism that produced the sinful nature? However hard those Christians try, they cannot remove the blame from God.