For people today, it can be difficult to see what the problem with Christian art is, or ever was. But it was a problem nonetheless, and a very serious one. So let's set out some considerations and some links about graven images.
The problem is a result of the conflict between two systems which were seen as "true" - Classicism, and Christianity. Both these systems are ultimately spiritual ones, both seek to explain the origin and destiny of the universe and the human soul. Needless to say, they do not agree on all points!
But Classicism was the older system and this has implications. It means that the Classical way of thinking was already well established as a mindset when Christianity became legal and widespread, and therefore Christianity was applied through a Classical filter.
Thus Classicism recognizes truth through orthodoxy (that is through ancientness, repetition, and pedigree). In other words, the longer a thing has been said to be true, and the more prestigious the original author, the more validity it has. That is the first important consideration. Even if we do not regard the tenets of Classicism as true today, they were nevertheless true and binding in the Middle Ages.
Classicism also finds that truth is universal. That is, truth is truth is truth. One truth cannot conflict with another truth. That is the second important consideration. It means that where Classicism and Christianity (which traces its origin to God, the oldest and most prestigious entity in the universe) conflict - something has to be done to reconcile them.
Classicism postulates a channel to and from the divine through beauty (we'll call it Classical Beauty to emphasis its difference from personal taste). It recognizes painting and sculpture as forms of beauty, capable of ennobling the soul and/or manifesting the divine. BUT Christianity has to contend with the Second Commandment which apparently forbids "graven images". That is the main problem: the Church had to find a way to produce images that were not images, paintings that were not paintings, sculptures that were not sculptures.
But there is a knottier problem than this. There is a problem with the actual meaning and intention of that commandment. This problem is, in fact, reflected in the number of different translations and renditions of that commandment - and so it is vital to cite your source when you quote it, exactly as you would for any other quotation: Deut 5.8, or Ex 20.4 - won't cut it. We need the edition too. Check these examples:
The King James Bible renders the text this way:
Thou shalt not make unto thee any graven images, or any likeness of anything that is in heaven above, or is in the earth beneath, or that is in the waters under the earth; you shall not bow down thyself to them, nor serve them.
Note the phrase "any graven images". Firstly, the word "any" seems to ban all such images. Then, secondly, the translator has used the word "graven" as his best guess for the real meaning of the original word, pesel or peçel. That word means "image", but is often interpreted as "idol". This interpretation apparently rests on the grounds of this commandment context alone, so let us consider pesel in more detail.
Pesel's root word is pasal or paçal, which means "to cut, hew, or hew into shape" - there is no connotation of idol-making whatsoever, so the interpretation of pesel as "idol" seems unjustified, strictly speaking. The English word "graven" is a fairly neutral term which means "drawn", or "engraved", or "carved". The term graven image therefore seems to be a good one, capturing the literal meaning of pesel (image), and also its root meaning (cut, engraved, carved). So the commandment seems to be that, "you shall not make any carved or engraved images".
But note also the follow-up, "you shall not bow down to them". In this light, it is possible to argue that the intention of this commandment is to ban idolatry, and not to ban figurative art outright. We can see the temptation to force that issue by replacing the idea of a carved or engraved image with the idea of an idol. That does not justify doing so, however!
So how do we understand this commandment? Most of us don't bother much today - we are so accustomed to religious art, and we also know ourselves free to believe or not to believe as much or as little as we like, that it doesn't seem to matter. This whole thing looks suspiciously like molehill mountaineering. To show you that it is not, look at these two links which show today's passionately continuing interest in these problems (they do considerable violence to their sources - let's do better in our own work):
Now notice, those authors use different translations of the text in question, and use them to argue diametrically opposed positions - and neither of them give you their source, either (very unscholarly). So let's look at some more sources:
The New King James Version renders the text differently:
You shall not make for yourself a graven image - any likeness of anything that is in the heaven above, or that is in the earth beneath, or that is in the water under the earth. You shall not bow down to them nor serve them.
Note what has happened to that first clause: the word "any" has vanished from it. So the command immediately becomes less all-encompassing, and it becomes possible to argue more strongly that the intention of the command was to ban idolatry, not art. The word "graven" continues as a convenient neutral term. This interpretation would be a useful step towards reconciling the Classical and Christian positions.
The New English Bible is different again:
You shall not make a carved image for yourself, nor the likeness of anything in the heavens above, or on the earth below, or in the waters under the earth. You shall not bow down to them or worship them ...
OK, this translator has taken a decision! The neutral word "graven" has been rendered by the stronger word "carved", i.e. "sculpture". By this interpretation, you could argue viably that the commandment forbids sculpture but NOT drawing and painting. Well, that is even more helpful for reconciling the Classical and Christian positions. Note also what has happened to that last sentence. What you now shall not do is quite explicit: you shall not "worship" such images. This effectively deflects attention from the business of the images to the business of idolatry.
But here is yet another version, this time from the New Revised Standard Version:
You shall not make for yourself an idol, whether in the form of anything that is in heaven above, or that is on the earth beneath, or that is in the water under the earth. You shall not bow down to them or worship them ...
This translator has taken an even more radical decision. The whole issue of technique has been passed over in favour of the assumed intention of the commandment. The "graven image" has been replaced by the interpretational word "idol", and what you shall not do continues to be "worship". The position is now very clear. Idolatry is banned, and art (whether sculpture or painting) has nothing to do with the case. It is not even mentioned.
Finally, look what the New American Standard Bible makes of the same commandment:
You shall not make other gods besides Me; gods of silver or gods of gold, you shall not make for yourselves. You shall not worship them or serve them ...
Here, we seem to have left translation behind altogether in the name of what we might call "Christian Correctness"!
Notice how each of these translations shifts the terms and interest one degree, until the one at the end has moved very far from the original text. You might want to consider the implications of that.
Just to remind you how far this translation has moved from the original, here is what Young's Literal Translation produces:
Thou dost not make to thyself a graven image, or any likeness which [is] in the heavens above, or which [is] in the earth beneath, or which [is] in the waters under the earth. Thou dost not bow thyself to them, nor serve them ...
Big difference, wouldn't you say?
Now, these are modern translations, but we can assume that the same issues plagued ecclesiastics in the Middle Ages, and that they took the same range of stances in relation to them. That is why it is not enough to present one's most familiar text as if it was the only possible one. You must say which it is, and you must consider the problems of translation, interpretation, and politics.
Yes, I did say politics. The translations I have cited above have a political agenda. After four hours of searching the web for clear explanations, I was shocked to find that all authorities skirt the issue of whether or not figurative art is lawful for the Christian, and focus attention instead on the business of idolatry - sometimes even going so far as to pretend that the art issue does not exist. Why might that be, do you think?
And bear this in mind too. Doing violence to your evidence in the name of correctness, orthodoxy, or religion, is dishonest! Be sure to hold yourself to a higher standard. The truth is so much more rich and interesting than groupthink.