Images have always played an important part in teaching Christians about their faith. However, Icons are much more than religious pictures. They are a way of telling people about Christian teaching in a simple form that anyone can see and start to understand. Icons in the earliest days of the Church were a means of depicting Gospel events (well before the New Testament was compiled) to Christians who were not able to read the biblical texts.
Orthodox Christians emphasize that it is both wrong and impossible to make a picture showing what God looks like. Humans can never see God in this world and often hardly know Him. Hence, we cannot have images of Him. However, God came into this world as a person. He became flesh and blood in Jesus Christ, the incarnation. That God became a human being is one of the most fundamental of Christian teachings. Therefore, we can paint a picture of Christ, because He lived here on earth.
The meaning of Icons reaches far beyond. In Icons of the Saints, for example, the pictures do not look like pictures of ordinary flesh and blood. They look strange. The Church teaches that Christ had a human body in order to save our bodies as well as our souls. At the end of time, when Christ will come again, everyone will rise from the dead. We will not look the same as we do now. We will be utterly changed, and we will shine with the glory of God. Icons show people with that sort of body – a resurrectedn body. The Church also teaches that all people are made in the image and likeness of God. In a way then, the Saints are living Icons of Christ.
The Gospels tell us in the story of the transfiguration on Mount Tabor, the Apostles saw that Christ was shining with light (Matt. 17. 1-13; Mark 9. 2-13; Luke 9. 28-36). Similar experiences happen to people who live a very holy life. When they are deep in prayer, they shine with a mysterious light. Their bodies have been changed, so that they show the image and likeness of God. Though not all saints show this sort of outward holiness. More often they grow into the likeness of God in a less visual way, but all Icons of the saints show that they have already changed from the ordinary to the divine (Theosis). Hence, saints are depicted with a halo around their head.