I read all your replies/comments, and so mine will be a general reply.
When we strongly believe in something and no one seems to support us, we tend to deviate from the trend and establish our own. When we have big problems and nothing we can do to solve it, we tend to lost our faith, like most people do. Or, if we overfed ourselves with recognitions and praises, we tend to break the rules and became "hard headers."
Remember that the first proponent of "evil" was Lucifer. He was one of the "archangels" who received a high position in the Heavenly Kingdom. He was called the "Morning Star" or the "Light Bringer" who supposed to lead the other angels for a heavenly purpose. But because of the "free will" he failed to do so.
So, we can now designate a point how evil came to limelight; it is because of "free will." But what is "free will" then?
Free will is the absolute autonomy of both man and spirit in decision-makings. It is an independent administration of one’s decision which is being justified by its execution. Free will is maybe a right that all entities are enjoying, and is "beyond the control of God," but it must be distinguished from freedom because the latter is just a component in the execution of the first.
Free will is a gift to all creations from the very moment they became what they are. It enables them to pushthrough on their assigned tasks. It is the prime essence of life. It makes life so purposeful because it gives every entity the absolute power to decide for themselves.
Now, in the programs of God, He also made laws for His creations. Why? Because God knew that what He was doing were all on "expiremental stages" and certain "rules/limitations" must be established in order to satisfactorily reach His objectives. Without the rules He may not perfected the plan.
So, what is "evil" then? The word "evil" is not the same as "devil." Evil is the state/condition/classification of an action which implies a blatant violation of the laws of God. The "devil" on the other hand is a term which refers to the "proponent of evil acts." At first, the word "lucifer" doesn't imply a "devilish" connotation but with "angelic" significance. It was only after "Lucifer" had committed his sin when the term/word became what it means now.
Of course, God created everything with good purposes. It is only during the process of "maturation" of His creations when certain "unaviodable" circumstances occur. Why? Because of the "Law of Nature" which is also the very force responsible for the maturation of His creations.