Good and evil co-exist within the same realm. Taking a cue from the biblical story of creation, in the same space where God comes to commune with the climax creation Man, also came the Devil. There is no written record of where the Devil came from or how the Devil arrived there. Becoming aware of this co-existence, the question that then arises is, which will prevail? That which prevails per time depends on the inclinations of the soul in question. Remember, it is with the soul that we express ourselves to the world around us.
Let's use the example of a room with a functioning light bulb. There are times when we want the room lit, to read, to search for something or to just enjoy the ambiance of light. For these and other reasons, we switch on the light. What happens is, the light shines and the darkness that was once everywhere now recedes, almost immediately, but it does not disappear as we've been made to believe over time. It just recedes into the corners or behind any structure, as made evident by any shadow that is cast. And if we want the room dark, again for whatever reasons, we just switch off the light. The light does not disappear either. It just remains in its source, sort of like on standby, waiting to be activated again when required. But the truth remains that there are times we want the room lit, and there are times when we want the room dark. Our soul is like a sword with two edges. The edge you need is the edge you use. And usually, the edge which is sharper is the edge you use. The side you lean more toward is the side you express, because it's the side of you that you're more familiar with and more prone to showing. And the side that you express ultimately becomes the side that you're known for and characterized by. But regardless of which side of the sword you're using, the bottom line is that we all have the two sides of the sword at our disposal.
And taking another cue from the story of the room and the light bulb, a truth is this: that there are some of us who want the room lit most of the time, and there are some of us who want the room dark most of the time. The need for more light or more darkness rests heavily on who we've decided in our hearts that we want to be. That person can only be hidden for so long, because eventually, the rest of the world around us will begin to see us for who we truly are...bringers of light, or harbingers of darkness.