Brothers and sisters, live as children of light, for the fruit of the Spirit is found in all that is good and right and true. Try to find out what is pleasing to the Lord. Take no part in the unfruitful works of darkness, but instead expose them. For it is shameful even to mention what such people do secretly, but everything exposed by the light becomes visible, for everything that becomes visible is light. Therefore it says, “Sleeper, awake! Rise from the dead, and Christ will shine on you” (Isaiah 26:19, 60:1). Be careful then how you live, not as unwise people but as wise, making the most of the time, because the days are evil. So do not be foolish, but understand what the will of the Lord is. Do not get drunk with wine, for that is debauchery, but be filled with the Spirit, as you sing psalms and hymns and spiritual songs among yourselves, singing and making melody to the Lord in your hearts.
Light vs darkness is a prominent theme in Christianity. Without God, outside of Christ there is only darkness. As the Lord said, "I am the light of the world. Whoever follows Me will never walk in darkness but will have the light of life" (John 8:12). Through Christ we go from darkness into light, we become the children of the light. And as such, we are capable of doing "all that is good and right and true."
Since we are the children of the light, Saint Paul exhorts us to avoid the unfruitful works of darkness. What is the point of becoming a Christian only to continue to languish in darkness and filth? Instead, Paul says to expose these unfruitful works of darkness. Being Christian does not mean that we are not tempted by the evil one. Satan does not care about those who are already in darkness, but he hates the light and can't stand that some of us might leave his grasp. Therefore, he attacks all the more those who at least strive for the light.
Being tempted as Christians, we have an advantage. That advantage is Christ, and His Church, and the sacraments through which He acts in His Church. When Paul says to expose the unfruitful works of darkness, I think, he means, first of all, our own unfruitful works. We have the tools in place, use them! Tools such as confession that allows us to do self-examination, in order to expose anything that is still dark in us, and present it to the Lord in repentance (literally, a 180 degree change of mind and/or behavior), so that in co-operation with Him we might be filled with light.
"Everything exposed by the light becomes visible." For this reason, it is impossible to come in contact with Christ and remain the same no matter how good we think we are. In Christ, in His light, we can be better. No matter how sinful we think we are, in Christ, in His light, the only thing we would want to do is change for the better.
When I say that we change when we come in contact with Christ, I do not mean that He changes us whether we like it or not. Our change, our salvation, is our co-operation with the will of God. Yes, God can do whatever He desires, whenever He desires it because He is all-powerful. And He desired to give us a free will, so that it would be our choice to choose to follow light or darkness. And these are the only two choices - light and darkness, there are no half-lit or half-dark places.
So, how do we determine whether we are in light or in darkness? Look at what you do, what you think, how you act. Are they "all that is good and right and true"? This is a simple, yet serious self-examination question. We need to be honest with ourselves when we attempt to answer this question. And we need to be open and honest before the Lord when we look at ourselves.
No doubt (I hope), some of our actions and thoughts and feelings are good and right and true, fully reflecting the light of Christ. And we also have acts, thoughts, and feelings that are dark. They become illumined by Christ when we are honest and humble. Darkness disappears when light enters.
Examine yourself. Watch everything that you do, think, and feel. Whatever reflects the light of Christ, give thanks and glory for that. Whatever is still dark, acknowledge it before the Lord, confess it, repent of it, let Him work in you, and work with Him to see the light.
Yours in the Lord,