Into the Wardrobe

Whatever framework you presuppose, whatever worldview you accept -- tacitly or explicitly -- there nonetheless remains a fact: the very end which human nature fundamentally and necessarily (though not necessarily consciously) seeks to attain is the final cause (in the Aristotelian sense) of all good and evil. That end is peace, joy, and love, or, as they say in the East, being, bliss, awareness. This is only to say we necessarily seek the good, we have no choice; the choice comes in choosing the means to that end, so that evil is a lack, a failure to progress towards that end. Aristotle noted long before Christ was born that man desires nothing solely for itself -- with the exception of happiness. Lewis essentially says the same thing in Mere Christianity, "badness… turns out to be the pursuit of some good in the wrong way." If particular goods are means chosen for the sake of one end, happiness, then that end determines what in fact is "the wrong way", thus what is bad.

This understanding can be taken in a multitude of directions.

Atheism's condemnation of religion, for example -- granting their worldview for the sake of discussion -- is purely a diagnosis of the symptom and not the cause. This must perpetually be the case since their incomplete worldview will not allow for an obvious fact: man necessarily desires what the world does not contain. It is the object of this desire, on any supposition, which must give rise to religion in the first place. To have what Atheist's want would be to somehow cut out of humanity the driving essence, the very inner spring which defines man as man -- it would be to cease to be fully human, or human at all. But any good motive -- and this is the rub for the Atheist -- is defined as good by the end. The motive of the Atheist, however, is different not in degree but in kind from any other motive. To want to cease to be human in this sense is literally nonsense, for it is saying at one and the same time that the end which drives all motives is both transcendent happiness and the annihilation of the drive of happiness (in other words it violates the law of noncontradiction by saying we're driven by an end and at the same time not driven by that end). Therefore the only real remedy for the Atheists diagnosis is to promote a set of actions and beliefs which are open to this transcendent end and logically contain natural virtue as their foundation. Only religion, in principle, can allow man to become fully man; atheism can only irrationally hope to eradicate man by the abolition, in principle, of religion.

Concerning Original Sin in general, the story of the fall of Adam implies that man was more complete than he is now, but had not entirely attained happiness -- inseparable union with God. He still had certain trees of which to partake. He still had a sacrifice of self to offer to God. This he did not do, and we can only suppose that he had sufficient knowledge in order to sufficiently reject the allure of self which we can also suppose held some promise of happiness not to the intellect, perhaps not to the will, but to the immediately felt desires of the incomplete self instead, which, oddly, to him, arose in the midst of his beatitude and did not belong.

Concerning Original sin in the Catholic/Protestant debate,

Evangelicals teach that Adam was created at zero, and, when he fell into original sin, he fell to negative one. Catholics teach that man was created at zero and immediately given extra gifts that brought him to positive one. When Adam fell, mankind descended to zero but still was fully human. --David Currie

The Existence of Original Sin. Chesterton said original sin was the one obvious and directly verifiable doctrine of Christianity. The mere fact that man is not naturally virtuous and happy, that there is a good God and that evil exits, is to me what Chesterton was talking about. Regardless, anyone going around denying original sin flat out contradicts himself if he at the same time affirms Lord Acton's famous political axiom that "power corrupts; absolute power corrupts absolutely." If in fact he doesn't affirm this, let him live in a society which also denies it, it will be eventually affirmed for him by direct acquaintance.