Those Who In Principle Reject The Icon, Ultimately Also Reject The Mystery Of The Incarnation

"Should somebody say, 'Since I ought to venerate [Christ] in spirit, it is pointless to venerate him in his icon', he should know that with this he also abandons the spiritual veneration of Christ. You see, if he, in his spiritual contemplation, does not behold Christ in human form at the right hand of the Father, then he does not venerate him at all. On the contrary, he denies that the Word has become flesh. But Christ's icon is a reliable testimony to the fact that the Eternal Word has become one like us."

"The painted image is for us a sacred light, a salvific monument, as it holds up before us Christ in his birth, his baptism, his miracles, on the cross, in the tomb, in his Resurrection and Ascension. In all this we are not being deceived as though these events would not have happened. For what our eyes see supports our spiritual contemplation, so that through both experiences our faith in the mystery of salvation is strengthened."

"Imprint Christ....onto your heart, where he [already] dwells; whether you read a book about him, or behold him in an image, may he inspire your thoughts, as you come to know him twofold through the twofold experience of your senses. Thus you will see with your eyes what you have learned through the words you have heard. He who in this way hears and sees will full his entire being with the praise of God."

"No matter how perfect he may be, no matter that he is clothed with a bishop's dignity, he nevertheless still needs the book of the gospels as well as its visual presentations. For both are equally venerable."

"What you think to be improper and coarse is on the contrary godly and sublime, if you keep in mind the immensity of the mystery. For is it not an honor for the Almighty to humble himself, in the same way as the humble would be ashamed to be exulted? Thus it is with Christ: he does not abandon the exalted reality of his divinity, which is immaterial and cannot be circumscribed; and yet it is his glory to abase himself in such a noble manner down to our level that now in his body he can be circumscribed. He has become matter, that is: flesh, he who sustains everything that exists; and he is not ashamed to have become what he has taken on (namely, flesh), and to be called such."

-St. Theodore the Studite

For more info on the Icon controversy and a great book on the early Christological controversies as well, see Christoph Cardinal Schonborn's book God's Human Face: The Christ-Icon.