This next passage, Luke 11.33-36, is still in the same context as was discussed in v.29-32 – that is, the Jews have sought a sign from Jesus but he has categorically denied them of any and also refuted them that he drives out demons by demonic forces. They are without excuse concerning their blasphemy. And so, Jesus preaches a sermon to them, calling them, it would seem, to leave a life of darkness and be “full of light, with no dark part” in them.
Jesus begins by explaining the purpose of a lamp: not to be hid but to provide light. Duh! Its designed purpose is to give light to everyone. And so be put in a place where is does not good is ridiculous; it belongs on its stand giving light. Jesus mentions a similar teaching in Matt 5.14-16 concerning the Christian’s life.
In this instance, though, he is driving toward the point that the eye, which is to illumine the whole body, if “bad” (or “evil”) will cause the whole body to be “full of darkness.” But if it is “good” (or “healthy”) then your body is “full of light.” As the song children learn goes: “Be careful little eyes what you see.” If we allow our eyes to be bad, that is too look and watch and read things that are “darkness,” we become a person who is “full of darkness.” In fact, though we should be “full of light,” that light becomes darkness (v.35). The apostle John wrote concerning this very thing in 1 John 1.5: “God is light; in him there is no darkness at all.” Hence to be where God is, we need to fill ourselves up with light for God can having nothing to do with darkness. John goes even further when he says, “If we claim to have fellowship with him yet walk in darkness, we lie and do live by the truth” (1 John 1.6).
This seems to be what Jesus is driving at: To be a person “full of light,” we must rid ourselves of all the darkness that can rob us of our light. James says it this way: “Get rid of all moral filth and the evil that is so prevalent and accept the word planted in you, which can save you” (James 1.21). And that is it: darkness is moral filth, evil, wickedness. Hence, light is that which is absolutely morally pure and perfect, since in fact that is what God is. Like standing in the light of a lamp, so you will be full of light. Let us strive to be where our Lord, in the light, free from wickedness and sin.