Newman and Chesterton on Original Sin

Newman, reflecting on the pervasive presence of evil in the world, "the blind evolution of what turn out to be great powers or truths… the disappointments of life, the defeat of good, the success of evil… the prevalence and intensity of sin, the pervading idolatries, the corruptions, the dreary hopeless irreligion…" (Apologia pro vita sua, 242) says that were he not certain of the existence of God, "I should be an atheist, or a pantheist, or a polytheist when I looked into the world." (Apologia pro vita sua, 241). He intends this as a statement regarding his own person, and not as a critique of arguments for the existence of God. Nonetheless he seems to take the presence of evil as objective evidence in favor of either (1) the non-existence of God, or (2) the existence of original sin:

What shall be said to this heart-piercing, reason-bewildering fact? I can only answer, that either there is no Creator, or this living society of men is in a true sense discarded from His presence…. I argue about the world; if there be a God, since there is a God, the human race is implicated in some terrible aboriginal calamity. It is out of joint with the purposes of its Creator. This is a fact, a fact as true as the fact of its existence; and thus the doctrine of what is theologically {243} called original sin becomes to me almost as certain as that the world exists, and as the existence of God. (Ibid., 242-243)

Chesterton also appears to take the manifest fact of evil in the world as proof that either (1) God does not exist, or (2) if he does, then that there is an original sin which accounts for the this evil:

Modern masters of science are much impressed with the need of beginning all inquiry with a fact. The ancient masters of religion were quite equally impressed with that necessity. They began with the fact of sin — a fact as practical as potatoes.  Whether or no man could be washed in miraculous waters, there was no doubt at any rate that he wanted washing. But certain religious leaders in London, not mere materialists, have begun in our day not to deny the highly disputable water, but to deny the indisputable dirt. Certain new theologians dispute original sin, which is the only part of Christian theology which can really be proved.  … The strongest saints and the strongest sceptics alike took positive evil as the starting-point of their argument. If it be true (as it certainly is) that a man can feel exquisite happiness in skinning a cat, then the religious philosopher can only draw one of two deductions. He must either deny the existence of God, as all atheists do; or he must deny the present union between God and man, as all Christians do. The new theologians seem to think it a highly rationalistic solution to deny the cat. (Orthodoxy, "The Maniac")

Now, Chesterton's principal intention is to argue against the position of "certain religious leaders," naming R.J.Campbell, and thus he may not directly intend to affirm that original sin may be proven in every respect from the fact of evil. Nonetheless, the question remains, in reading both Newman and Chesterton: is the existence of God in fact compatible with evil only if one postulates original sin? Or are they making an implicit, unreasoned identification between the existence of "God" and the existence of the Christian God, with the kind of providence  that Christians believe God has for man?

James Chastek made a post a few weeks ago that touched upon the same question from another point of departure, which readers of this blog may also be interested in: Who believes in the God that the argument from evil would seek to refute?