Well, it is about opposites I suppose. There is, so there is not. We all have freedom of will, and with it we may reject what is in favour of what is not. Evil is anti what is - antilife - antitruth - antichrist - antisocial - antilight - pretty much all the opposite. We are either for Him (truly for life) or against Him (for what is false).
Sin is the alienating behaviour that results from choosing what is not truth, evil. By eating from the tree of knowledge of good and evil man took on board the false idea, which is that you know right from wrong, or what is good or corrupt, independent of Him. Then it was for love of us that He kerbed us living forever independently. To see us living forever in darkness of mind was grieving to see - we are greater than the other animals.
Who can bear seeing loved ones living a lie? Isn't that why people post on this board? What grief it causes, and how much suffering is too much when knowing a good outcome - is it no amount?
The antitruth or nothingness is inherrant to the current worldly man. The choice for nontruth comes from other than God, "and without Him was Nothing made that Was made". We and the evil or opposite one labour the corruption of creation - we should enter the Sabbath, at least have Sundays off it.
Evil doesn't necessarily know, and may even deny, that it's evil, becoming bound - a lie about a lie - "loose him and let him go" etc. Evil is the movement toward the dark, or death - but He overcame death for us, after man chose it - nothing is impossible for Him.
Bang