Just sort of shotgunning here are a number of responses:(1)
1st. Century Images: Given the stretches of time involved the survival of such artifacts to this day are unlikely, though not impossible. There are at least 4 or 5 images of the Theotokos that are reputed to be originals from the hand of St. Luke. Be that as it may, as ancient as these images are they bear the marks of numerous touch ups and repairs across the centuries…so ascertaining the how much of the original work is left may not be possible.
We must also bear in mind the ravages of the iconoclasts. We have no way of knowing how much from the most ancient times they destroyed, or how much of that deposit was later destroyed under the rule of image hating Islamists.
That said there are a few documents that bear witness to some very ancient images that were known to the authors of these accounts. In the History of the Church compiled by Eusebius he recounts seeing with his own eyes the double bronzes images set upon the gate posts of the house of the woman healed of the issue of blood. One was of a woman kneeling in posture of supplication, the other was of a man with the features of Jesus, wearing a double cloak about his shoulders and with his hand extended towards the woman supplicant. This set of images was reputedly raised by the healed woman herself. (Book 7 chapter 18).
Eusebius said he had also seen old images/portraits of Christ and of Sts. Peter and Paul. Given that Eusebius was an active Bishop in the early 4th century, that would strongly suggest at a minimum the images he had seen belonged to the third century if not sooner. St. Gregory of Nyssa, also from the early to mid 4th century mentions very moving representations of the Passion of Christ and the Sacrifice of Issac.
As to the sign of the cross, here is a passage from Tertullian from the 2nd Century:
"Caro abluitur ut anima maculetur; caro ungitur ut anima consecretur; caro signatur ut et anima muniatur; caro manus impositione adumbratur ut et anima spiritu illuminetur; caro corpore et sanguine Christi vescitur ut et anima de Deo saginetur" (The flesh is washed, in order that the soul may be cleansed; the flesh is anointed, that the soul may be consecrated; the flesh is signed [with the cross], that the soul, too, may be fortified; the flesh is shadowed with the imposition of hands, that the soul also may be illuminated by the Spirit; the flesh feeds on the body and blood of Christ, that the soul likewise may have its fill of God — "Deres. Carnis.", viii). (from: http://www.newadvent.org/cathen/14520c.htm)
From the same source:
The cross was originally traced by Christians with the thumb or finger on their own foreheads. This practice is attested by numberless allusions in Patristic literature, and it was clearly associated in idea with certain references in Scripture, notably Ezekiel 9:4 (of the mark of the letter Tau); Exodus 17:9-14; and especially Apocalypse 7:3, 9:4 and 14:1. Hardly less early in date is the custom of marking a cross on objects — already Tertullian speaks of the Christian woman "signing" her bed (cum lectulum tuum signas, "Ad uxor.", ii, 5) before retiring to rest—and we soon hear also of the sign of the cross being traced on the lips (Jerome, "Epitaph. Paulæ") and on the heart (Prudentius, "Cathem.", vi, 129). Not unnaturally if the object were more remote, the cross which was directed towards it had to be made in the air.2.
The origin of icons of the saints and martyrs in Egyptian funerary customs: There are a number of reference works on the history of iconography that mention this. One of note is Iconostasis by St. Pavel Florensky, the physicist, iconographer and martyr of the early 20th century. One may see examples of the early types of these portraits in encaustic in the Fayoum images: http://en.wikipedia.org/wiki/Fayum_mummy_portraits3.
Bible and Image: So let's see:
1) No proof of 1st century Christians venerating or using icons in the church - Check
2) Disobeying the 1st Commandment, making an image in the likeness of things in heaven - Check
3) Disobeying the 1st Commandment and serving them - Check
4) Disobeying the 1st Commandment and bowing down to them - Check
I really hope you see my cause of concern here. Simply look at that photo & READ THE COMMANDMENT. Icons in ornate served settings, being bowed to by clergy like that... The likenesses of things in heaven. No proof in the 1st century, and very little proof of icons until the 4-5th century.
Let's examine your argument: No first century proof. Well, if you read above some proof is provided from the time of Eusebius that 1st century images existed. Granted the particular 1st century image he mentions was a statue and while it was cherished by the Christian community of his time, there is no particular reference to it's veneration or of it being treated like icons came to be treated in the Church. Historically, I believe the last mention of these bronzes was in the 6th century. Still, it establishes that images of Christ were known in the Church of the 1st Century…not that such a thing should matter too much. The mention of portraits of Christ known to Eusebius and to St. Gregory put the use of flat images/portraits easily within the 3rd century, and strongly suggests they these must rest on earlier 1st century models….that was not the sort of thing honest Christians would just make up or other honest Christians take up unless such things had roots in Apostolic times. The reason such an assertion can be made is because it was these same men in the 4th century testifying of images in the Church who were responsible for compiling the Scriptures of the New Testament and joining them with the other attested works of the Old Testament as Scripture for the Church?
Where did the Lord ever give the command that any of His Apostles should compose narrations of His life and Crucifixion and Resurrection? Where did the Lord or the 12 ever command that the Letters of St. Paul or any of their own letters should be collected and compiled together with the Gospel accounts as new Scripture for Christians. Nowhere. So how did these writings become Scripture? They were preserved in the churches for whom and to whom they were first written. They were treasured, shared, copied and passed from one Church to the other….this is enough to grant they were very inspirational writings, but by what authority were they edited here and there to stitch in missing bits of the respective apostolic tradition (like the end of the Gospel of St. Mark), and by what authority were they raised to the level of and used in the Churches as Scripture? It can only be the authority of the Church itself, which is the Bride of Christ, the Church of whom St. Paul says that it is the pillar and foundation of all truth; the same church that he directs to keep both the written and the unwritten tradition in his epistles.
If that God given, God ordained authority is sufficient to establish the authority and use of NT Scripture in the Church for it's teaching and edification, then why is it somehow insufficient to establish the use of images to teach the same things in line and colors as it did in words scribed in pen and ink? You cannot accept the testimony of the Scriptures and at the same time refuse icons, for it is the same Church working by the same Holy Spirit given authority that gives us them both.
It does not matter than no first century evidence of icons remains anymore than it matters that no first century autographs of the Gospels remain. The form the Scriptures had attained by the 3rd and 4th centuries when authoritative collections were listed and gathered to counter the false writings of the heretics…that is the form that matters most, for that is the form that gives us the present text of our New Testament Scriptures. The various local image traditions of the first generations of the Church matter mostly as historical footnotes. The images that matter are those sanctified and established in the Church when their content had matured and standardized across the Church so that it embodied visually the fullness of the theological teaching and life of the Church.
You cannot have the Bible and reject the Church that gave it to you, nor can you have it and reject the Divine Liturgy, the veneration of the Saints, nor the use and veneration of the icons of those same Saint. You might as well say you accept water but reject wetness. It's all the same fountain.
Violation of the first commandment: It is true God said not to make an image of Himself in His commandments to Moses. Was there a reason?
Why could Moses and Aaron use symbols of various beasts and plants and make images of angels, but not of God? Might not it be that God had not yet revealed His own image in time and history. Do you believe that Jesus Christ is God incarnate? Do you believe Jesus if both fully God and fully man? Do you believe if brownie instamatics or video cameras had existed in the first century that anyone who got close enough could have taken a photograph or made a home movie of Christ talking to his disciples, walking down a road, feeding the multitudes, or crucified one day on a Roman cross? Unless angels would have interfered in some way or a pillar of fire interposed between your camera and your subject…then an image of Christ in the world would have been possible. And if a photographed image is possible, then a sketched or painted one is possible as well. So what then does it mean with respect to images that Christ would be seen and photographed or drawn? Does it not mean at least that while He was not with us, there was no image we had for reference, but after He came, He supplied His own image in Himself. And thereafter that image could be recorded just as were His words, and just like His words, treasured and passed down among the faithful? The commandment is not broken. It is fulfilled. In the OT times God was heard, and His words recorded by the Prophets. In the NT God dwelt among us and was seen, heard, and handled of men, thus His words and His image were recored by His followers. In the OT an image of God would have been a blasphemy for no Image had been given. In the NT an image is not blasphemy if it is modeled on the Image God gave of Himself, rather it is a testimony to the fact of the Incarnation, that God indeed became man and dwelt among us.
Veneration of images. What gestures of respect/reverence are permissible to the faithful and what are not? What about the flag. We salute the flag and it's not an image…and technically not even a symbol. It is a sign of our country. Are you saluting colors and patterns on cloth? No, you are saluting what those colors and patterns point to. What if we saluted icons but didn't bow to them would that be okay? Why can't a bow serve as a type of salute. It is not our custom…but it is the custom in various Asian cultures. They are no more worshiping their flags by bowing than we are by saluting…but they are honoring their country which is represented by their flags.
Given that icons, the culture that they originated in and the customs of that culture are both far more ancient and far more eastern in mindset than Western Europe and European style saluting (which came into existence with knights raising their visors to be recognized.) bowing then as a gesture of respect may not be so far fetched. What given that in places Scripture forbids bowing to idols, yet has numerous examples of people bowing to kings (if they weren't being persecuted for their faith)…when is a bow showing such honor as may be shown a human in high authority, and bowing to some thing believed to be a god allowed or distinguished?
The Church answered that question in the 7th council (which right to hold authoritative councils is established in the 15th chapter of Acts). It said the veneration shown to an icon is the same as may be shown unto a man. It is not the worship reserved for God alone. It further says the honor shown to the icon is not to it's image as an image or to it's material components, but rather to it's prototype, the person depicted. If an icon grows too marred for recognition and hence for veneration it may as well be burned like firewood. So given the body has a limited physical vocabulary so to speak to show reverence or any other thing…some gestures have to do double duty…and people are trusted to have the brains to distinguish what is to be understood by that gesture.
I recall one day a few years ago a Protestant came to visit one of our services that just happened to be one of the feasts of the Holy and life giving Cross. The point came in the service where the people began to kiss and prostrate before cross starting with the priest, wave after wave of the faithful falling on their faces, in reverence. This young man literally collapsed like he was struck with a two by four. He could not stand…he just dropped to his knees trembling and weeping. When his friends (some of whom were members there) got him outside to compose himself, he sat on the front steps almost emptied of words, tears running down his face, saying over and over again…"It was so beautiful. It was so beautiful."