This gives us a great responsibility. We are Christ's spiritual light. Darkness is always, has always been with us. No era of human history has been devoid of great deeds of darkness. And individually, we were all, without exception, lost in the darkness until we were brought out of the darkness by the grace of God.
Darkness signifies spiritual ignorance and moral depravity.
To be in sin, the work of darkness. To live in sin is to be under the control of darkness. It is sin that keeps one in the darkness. To be under Satan, the prince of darkness. To be under wrath, the fruit of darkness.