Why did Christians fight about pictures?

"You shall not make for yourselves an idol, nor any image of anything that is in the heavens above, or that is on the earth beneath, or that is in the water under the earth: you shall not bow yourself down to them, nor serve them."

A movement that grew out of Judaism inherited that, took it seriously, and was mocked by its neighbours for having no statues of its god.

Colossians: "he is the image of the invisible God, the firstborn of all creation." The word is eikon.

If God cannot be depicted because God has no form, and the claim is that God took a human form with a face, then the prohibition and the claim are pointing in opposite directions, and somebody was going to notice.

The familiar account has imperial policy turning against images for most of a century, in two waves, with pictures destroyed wholesale, bishops deposed, and the monasteries leading the resistance.

Leslie Brubaker’s study of the period sets out to take that account apart, and argues that it was not an imperial initiative that destroyed images wholesale, that monks were not the main promoters of icon veneration, and that the age was not one of cultural stagnation. She dates the debate from about 680 to 850. What stands on the record either way is that emperors summoned the councils on both sides.

The west never made it policy, and did not simply take the answer either: Rome backed the images, while a Frankish council at Frankfurt in 794, working from a faulty Latin translation of the acts, condemned the council of 787.

The second council of Nicaea ruled that images "should be set forth in the holy churches of God", and that "to these should be given due salutation and honourable reverence, not indeed that true worship of faith which pertains alone to the divine nature".

Two different Greek words, proskynesis for the reverence given to an image and latreia for the worship owed to God alone. And the reason: "the honour which is paid to the image passes on to that which the image represents, and he who reveres the image reveres in it the subject represented."

Whether that distinction holds is the argument. That it was made, and made in those words, is a matter of record.

Candidate causes: a theological conviction about idolatry, pressure from a confident and image-free Islam on the frontier, military defeats read as divine displeasure, and a contest with monasteries that owned images, land and influence.

The iconoclast council’s own definition, of 754, is read today in the acts of the council that condemned it, where it was set out clause by clause to be refuted, which is a serious problem for anyone trying to reconstruct what that side actually argued.

Eastern Orthodoxy treats the council as settling it, and holds icons to be not only permissible but spiritually necessary. Catholic teaching went the same way: its catechism cites the council for the honour that "passes to its prototype".

Calvin rejected the distinction, in the form dulia against latria, and argued against the council of 787 by name, and the Heidelberg Catechism would not have images in churches even as books for the unlearned. The argument in the sixteenth century reads remarkably like the argument in the eighth. That is either a sign that the question is genuinely open or a sign that it recurs wherever the texts are read fresh.

Both councils claimed the older tradition for their own side. Each party was in a position to remove the other’s evidence, the council of 754 by ordering every likeness "rejected and removed", though how much was actually destroyed is itself now argued about.

And the written record is thinnest exactly where one side won decisively: the books written against the images were to be handed in "that they may be locked away with other heretical books".

Not a portrait and not an aid to concentration: on the Eastern Orthodox account it is a witness to the presence of the Kingdom of God, and the honour passes through it to the person, which is exactly what the council said and what its opponents denied was possible.

The council of 754 had denied it in terms of the incarnation: whoever makes an image of Christ "either depicts the Godhead which cannot be depicted" or represents his body as separate from it, and "the only admissible figure of the humanity of Christ" is the bread and wine of the Supper.

The strongest version of the opposing case is also worth stating plainly: that people do in practice treat objects as holy in themselves, that the distinction is invisible at the level of what anybody is actually doing, and that the commandment was given because this is what happens.