One defines evil as nothingness. Certainly evil never exists by itself but only inside of Goodness. Evil is a pure negation, a privation or a mutilation. Undoubtedly evil is a lack, a defect, defectus. But the structure of evil is rather antinomic. Evil is a void of nothingness; but it is a void which exists, swallowing and devouring beings. Evil is a powerlessness; it never creates--but its destructive energy is enormous. Evil never ascends; it always descends--but the very debasement of being which it produces is frightening. Nevertheless, there is an illusory grandeur even in this baseness of evil. Occasionally there is something of genius in sin and in evil. Evil is chaotic; it is a separation, a decomposition constantly in progress, a disorganization of the entire structure of being. But evil is also, without doubt, vigorously organized. Everything in this sad domain of deception and illusion is amphibolic and ambiguous. Undoubtedly, evil only lives through the Good which it deforms, but it also adapts it to its needs. But this deformed "Universe" is a reality which asserts itself.
Does that account reveal a true paradox, or does it run smack into logical contradiction?
The above passage is part of a much longer quotation from Florovsky at Ad Orientem, a blog I like because the author is Orthodox, intelligent, and willing to use a Latin phrase. One would do well to read the whole passage.