Of course, to most Christ did not outwardly appear to be anything more than a man. St Paul tells us He took the form of a servant. If others had outwardly seen Him as God, surely they would have treated Him differently.
And yet one of the times that specifically is called to be shown in holy images is that of the Transfiguration on Mt Tabor. (We recently celebrated the Feast of the Transfiguration, so this is fresh in my mind).
It's an interesting icon exactly for the challenge you describe. How do you present a transfigured Christ? This is truly the time when we should be the most careful. Other times, to present him being baptized is ok. We have good descriptors - a man, in the Jordan, being baptized; the Holy Spirit descending as a dove. But how do you show a man being visibly transfigured to show His true self, as much as the human eye and mortal body can bear?
Here's a picture.
There's a lot of elements here but what is key to your objection (i.e., how do you display divinity?) is in the
mandorla. This is an iconographic tool to depict His revealed majesty, glory, and divinity, while preserving the mystery of the godhead. It always accompanies Him in traditional icons of His Resurrection, Transfiguration, Ascension, the Dormition, and of Christ in Glory - because in these icons we show Him in his Glory, not Him as a man.
Mandorla is Italian for almond, and this has a significance of its own. The almond is a symbol of life and fertility; Aaron's rod in Numbers 17 produced almonds (the church fathers strongly link this rod with the Theotokos, who conceived supernaturally and inexplicably).
It represents more than what was seen but also what isn't seen, something beyond the physical. The "cloud" in the transfiguration account is represented by the mandorla. This is why the mandorla paradoxically gets darker as you move in - the greater the glory, and the greater the mystery.
Christ's hands in most icons are raised in blessing with His index and middle finger raised, showing His two natures; the thumb, ring, and pinky are joined together revealing the Trinity. In the traditional icon of the Transfiguration, instead Christ is offering a benediction with His thumb touching His ring finger, with the other three raised. This also represents His two natures, and the three persons of the Trinity, but His hands form the Greek monogram IC XC (first and last letters of Jesus Christ in Greek). This is another way to always know that the depiction is Christ.
His halo has the cross in it, showing the means of His redemption of man, as well as the Greek letters for He Who Is (traditionally -- in this case, instead there are three pips which denote the Trinity).
In this version, He carries a scroll, a likely reference to Psalm 40: "Behold, I come; In the scroll of the book it is written of me."
He is flanked on either side by Moses and Elijah - representing the Law and the Prophets. They also were two who wished to see God. Moses only saw His back, hidden in the cleft of the rock. Elijah heard the still small voice. Yet in this icon we see Christ revealing Himself to Sts Peter, James, and John "as far as they could bear it". Moses and Elijah are looking at God, while the Apostles are fallen, terrified. Even though they were chosen to be "eyewitnesses of His majesty...on the holy mountain" (2 Pet 1:16-18) they are terrified. A strong contrast to the static and peaceful depiction of the three above. This shows the contrast between the motionlessness, the peace, of the supernatural life; and the imperfection of even the three sinful men selected for this great honor. The peace of heaven is juxtaposed to the chaos of earth.
The hymns for the feast talk about each apostle being granted the vision of God as far as they could bear it. So St James is thrown down, St John covers his eyes, while St Peter covers his face and tries to look up and reach. I imagine also that this shows that at the glory of His second coming, we each will respond differently to Him, while His light shines on us the same.
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So, you're telling me this depiction is somehow blasphemous?