Without evil there can be no true love- If all we ever received in life were good from God, then we'd all not need to express any real true love toward Him- only when the love has been tried by things that would arrest our affections does it become clear what love truly is.
When love can endure through severe trials and tribulations, it becomes rock solid- when a person finds out what it means to truly love with no thought of getting anything in return, then they have plumbed the depths of desire and come away stronger than ever.
Evil gives man free will- it gives him an alternative objective to give his affections to. It's like when a man or woman gets married- they are of course devoted to hteir spouses, but the fact is, that connection grows stronger as they both are tried by encountering desires on the outside- yet remaining true to the spouse. (Not all are succesful of course, but hte ones that are have conquered their desires and become stronger in their relationship by deciding it isn't worth it to play the field)
There may be folks 'full of evil' here on earth- BUT they have NOTHING on Satan and ilk who are PURE evil- these evil folks will be shocked at how vile true evil is when they descend into the pit and face eternity. Satan and ilk hate God and God's creations so much that they are compelled by desire to completely destroy them- those practicing evil here on earth are in for an awful time in the afterlife- perhaps they feel that Satan will go light on them because they 'did His bidding' while here on earth BUT Satan will NOT! These evil folks will be screaming like little girls at hte sheer fright and terror hell will be to them. http://sacredscoop.com
Good and Evil are better understood from a Divine perspective available to us through faith in Christ.
Remember that the Adversary seeks to make himself like God. Just like the angels, God has given humans volition as well.
Additionally, after the Garden of Eden, one penalty for Satan was that God placed enmity in the heart of man towards him. Although Satan sought to counterfeit God's place in man's heart with himself, God changed the heart of man to always have enmity towards Satan naturally.
Although Satan might have a plan to counterfeit Paradise, even Satan is unable to prevent man in his volition from sinning. Many people too quickly associate our sin or rebellion from God's will with our identification with Satan. Nothing is further from the truth. Man hates Satan. If we rebel from God, many more rebel from Satan. Even though God might not control our volition by His choosing, likewise even Satan can't keep us from sin. We sin because we like to sin. We might be stupid, but we still have volition.
Love is not a complement to evil. The thought of giving without receiving anything in return is the definition of CHARIS or Grace, ..where we get our word Charity. Good and evil are better understood by understanding the meanings of righteousness and chaos. Faith places our trust in an an object that is non-meritorious of ourselves. All faith is from God.