The verse sounds complicated but really it's very simple. If there is a room and it's in darkness, and somebody lights a lantern and sets it up on a stand, then immediately you can see everything.
If you have got the light, you have got it. If Christ has shined into your life and given you a new life and forgiven your sin; if he has converted you, if he has given you a living soul so that you can walk with him and relate to him, then your whole being is changed and different. Your total person is affected by this. There is no such thing as being half converted or quarter converted. It's everything, or it's nothing. There's no such thing as being gradually converted over an entire lifetime. Some people speak like this: as if conversion is a lifelong process. ‘I am not there yet, but by the end of my life I shall belong to God.’ The Church of Rome teaches that conversion is a lifelong process. You never know whether you are going to make it until the last day. But that is not the conversion of the Bible. Says the Lord Jesus Christ, ‘If that light shines in through the window of your soul, and your life is lit up by the power of God, by Christ, so that you are converted to God; if he has worked a wonderful miracle in your life and you know him and you walk with him; if the light has come into your understanding so that you think differently; if it's in your will so that you want to obey him; if it's in your feelings so that you love him, then it isn't just half of you that is converted. All of you is gloriously changed and in a kind of crisis experience. It is true that it may happen over a few months. You may have a struggle sometimes, because you are not very quick to repent of your sin and to trust the Lord, and it may be that you are only aware gradually that God has changed you, but nevertheless your conversion, when it happens, is complete. You are not quarter converted this year, quarter converted next year, and so on. If you come to Christ and you repent of your sin, and you mean it, and you say: ‘O Lord, forgive me. Forgive all my sins, my inner sins, my evil nature, my deeds, my thoughts, my plans. I will obey you. I will be yours’, and you trust only in Jesus Christ, and how he died on Calvary’; if you come in that spirit, you will be transformed, changed, and made a true child of God. The light of the message of the gospel streams into you, so that you see yourself and your need. It shows the whole room, the way to the King, the way to God.