come, let us walk in the light of the Lord

In all of the gospels the Lord Jesus uses the imagery of light/darkness. Let us look at some of his words and meditate on their meaning. I'll focus on two key metaphors: not putting a lamp under a basket, and the eye being the lamp of the body.

First Matthew 5:14-16

In this passage we, the believers, are the light. We are to bring glory to our God by our actions. Our good works are what set us apart from the darkness around us, and what lights up that darkness. Our works are a revelation of God to the world around us. By instructing his disciples not to light a lamp and put it under a basket The Lord clarifies what it means to be a follower of Jesus. A Christianity that doesn't impact the way we treat others, and cause us to do good to our neighbor is no Christianity at all. It makes as much sense as a lamp under a basket.

Matthew 6:22-23
Here we first encounter the concept of the eye being the lamp of the body. For me at least the meaning of this was not immediately obvious. I think we can eliminate right away that Christ was talking about literal eye health as if what we really need is a good optometrist. The eye must be relevant in another way. One helpful passage which uses a similar metaphor is Ephesians 1:18 where part of Paul's prayer is for the eye of the Ephesians's hearts to be enlightened that they may know the hope to which God has called them. Like our physical eyes the eye of our heart's purpose is to perceive. We want our perception to be clear. Our perception is made clear by looking to God's revelation in Jesus Christ. Interestingly in this case the passage about the eye being the lamp of the body is sandwiched in between two passages about money (Vs.19-21 & 24). Taken altogether Vs. 19-24 are a clear warning against the love of money corrupting our perception. To be focused on money is to have a bad eye. To have a good eye is to not only know about Jesus , but to perceive his true value. Vs. 24 tells us we can not serve God and money. Christ's followers are called to a singular devotion to God. But in order to be devoted we must see Christ rightly.

Mark 4:21-23
In Matthew 5 we saw very certainly that the lamp not to be hidden under a basket was the works of believers. But in this passage I believe it has a different meaning. The passage in Mark 4 follows, and I believe relates to, the parable of the sower and its explanation (Vs. 1-20). Here the light that is manifest is the the message of God revealed to his followers. Earlier in the same chapter Christ said, "To you has been given the secret of the kingdom of God, but for those outside everything is in parables, so that 'they may indeed see but not perceive..." In this passage we are called to be those who perceive the truth that is to see the light revealed in Jesus Christ.

Luke 11:33-36
Here we have the only passage where the Lord combines these two metaphors speaking both of the lamp under a basket, and the eye as lamp of the body. Again we look to the context of the passage to gain understanding of the metaphors. Here preceding the passage Jesus deals with those who reject him seeking a sign (Vs. 29-32), and after the passage he again deals with opposition in the hypocritical judgment of the Pharisees (Vs. 37-41). In Luke the lamp is Christ himself. He is the revelation of God displayed before his adversaries. He was lifted up on a stand and not hidden, and yet they rejected him. He was the one greater than Jonah (Vs.32) that they did not accept. The focal point of the passage, again like Matthew 6, is perception. Those who perceive Christ properly are full of light, and those who do not are full of darkness. Where this passages stands out from the one in Matthew 6 is the encouraging picture of the one who fully looks to Christ in Vs. 36. This is our goal. This is what we are called to be: wholly bright as when a lamp with its rays gives you light. This also circles back to the first passage I mentioned where we are the light (Matt 5). When we fully perceive God's revelation in Christ we ourselves become a reflection of that light in the world.
By looking intently on our Lord's use of these metaphors we understand we are to rightly perceive Christ. We are not to walk in ignorance like those who do not know God, but to live in the light of his revelation. This relates very closely to the meaning of the parable of the sower. We are not to allow our eyes to be darkened by money like the seed that fell among the thorns. We are not to reject the light like the seed that fell along the path and Satan immediately came and took away the word. This is what he did to those who rejected Christ thought they saw him in the flesh. But we are to look to the Son of God. We are to hear his words, and obey him. We are to become lights ourselves.
Consider how gracious it is that God has given us any light at all. Without Christ all is darkness. All human learning and thinking takes place in the dark until Christ appears. But now the light shines.
Christ warned in John 12: 35-36, "The light is among you for a little while longer. Walk while you have the light, lest the darkness overtake you. The one who walks in darkness does not know where he is going. While you have the light, believe in the light, that you may be sons of light. "
That is the invitation which is held out to you.