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 [who deny the sin] think it a highly rationalistic solution to deny the cat."
G K Chesterton, "Orthodoxy"