Evil is but the shadow, that, in this world, always accompanies good. You may have a world without shadow, but it will be a world without light - a mere dim, twilight world. If you would deepen the intensity of the light, you must be content to bring into deeper blackness and more distinct and definite outline, the shade that accompanies it.
The truest definition of evil is that which represents it as something contrary to nature. Evil is evil because it is unnatural. A vine which should bear olive-berries - an eye to which blue seems yellow, would be diseased. An unnatural mother, an unnatural son, an unnatural act, are the strongest terms of condemnation.
If the one be good, the other must be evil. The only way to justify the stage, as it is, as it has ever been, as it is ever likely to be, is to condemn the Bible - the same individual cannot defend both.