Satirizing a practice shows that the practice existed.
Not that I'm one to agree with YiM on issues like this, but I do wonder if he has a point here. Is the graffito depicting a man worshiping before or venerating an image of the Crucified, or is it ridiculing the idea of a man worshiping a crucified man as God? What little reading I've done about depictions of the Crucifixion, the crucifix, etc. led me to believe that the development of the Cross as a religious image looks something like this:
"Empty" Cross --> Cross with a living Christ depicted as a king/priest --> Cross with the dead/dying Christ
If that's true, then this example of an image of a crucified man (albeit with an animal's head) is unique for its antiquity but doesn't really "fit" in the overall development. Is there something else I'm missing? I still think YiM's approach and most of his conclusions are nonsensical, but I wonder if this is a "stopped clock" moment...
The pagans had claimed that the Jews worshipped the ass, as Josephus has to protest:
However, I cannot but admire those other authors who furnished this man with such his materials; I mean Possidonius and Apollonius [the son of] Molo, who, while they accuse us for not worshipping the same gods whom others worship, they think themselves not guilty of impiety when they tell lies of us, and frame absurd and reproachful stories about our temple; whereas it is a most shameful thing for freemen to forge lies on any occasion, and much more so to forge them about our temple, which was so famous over all the world, and was preserved so sacred by us; for Apion hath the impudence to pretend that" the Jews placed an ass's head in their holy place;" and he affirms that this was discovered when Antiochus Epiphanes spoiled our temple, and found that ass's head there made of gold, and worth a great deal of money.
Tertullian towards the end of the second century responded to this calumny, and the extension of it (even by Jews) against the Christians:
In this matter we are (said to be) guilty not merely of forsaking the religion of the community, but of introducing a monstrous superstition; for some among you have dreamed that our god is an ass's head,--an absurdity which Cornelius Tacitus first suggested. In the fourth book of his histories, where he is treating of the Jewish war, he begins his description with the origin of that nation, and gives his own views respecting both the origin and the name of their religion. He relates that the Jews, in their migration in the desert, when suffering for want of water, escaped by following for guides some wild asses, which they supposed to be going in quest of water after pasture, and that on this account the image of one of these animals was worshipped by the Jews. From this, I suppose, it was presumed that we, too, from our close connection with the Jewish religion, have ours consecrated under the same emblematic form. The same Cornelius Tacitus, however,--who, to say the truth, is most loquacious in falsehood--forgetting his later statement, relates how Pompey the Great, after conquering the Jews and capturing Jerusalem, entered the temple, but found nothing in the shape of an image, though he examined the place carefully. Where, then, should their God have been found? Nowhere else, of course than in so memorable a temple which was carefully shut to all but the priests, and into which there could be no fear of a stranger entering. But what apology must I here offer for what I am going to say, when I have no other object at the moment than to make a passing remark or two in a general way which shall be equally applicable to yourselves? Suppose that our God, then, be an asinine person, will you at all events deny that you possess the same characteristics with ourselves in that matter? (Not their heads only, but) entire asses, are, to be sure, objects of adoration to you, along with their tutelar Epona; and all herds, and cattle, and beasts you consecrate, and their stables into the bargain! This, perhaps, is your grievance against us, that, when surrounded by cattle-worshippers of every kind we are simply devoted to asses!....Report has introduced a new calumny respecting our God. Not so long ago, a most abandoned wretch in that city of yours, a man who had deserted indeed his own religion--a Jew, in fact, who had only lost his skin, flayed of course by wild beasts, against which he enters the lists for hire day after day with a sound body, and so in a condition to lose his skin--carried about in public a caricature of us with this label: Onocoetes ["Ass-born"]. This (figure) had ass's ears, and was dressed in a toga with a book, having a hoof on one of his feet. And the crowd believed this infamous Jew. For what other set of men is the seed-plot of all the calumny against us? Throughout the city, therefore, Onocoetes is all the talk. As, however, it is less then "a nine days' wonder," and so destitute of all authority from time, and weak enough from the character of its author, I shall gratify myself by using it simply in the way of a retort. Let us then see whether you are not here also found in our company. Now it matters not what their form may be, when our concern is about deformed images. You have amongst you gods with a dog's head, and a lion's head, with the horns of a cow, and a ram, and a goat, goat-shaped or serpent-shaped, and winged in foot, head, and back. Why therefore brand our one God so conspicuously? Many an Onocoetes is found amongst yourselves.http://www.earlychristianwritings.com/text/tertullian06.html
In between Tertullian talks about the "worship" (i.e. veneration) of the Cross, which he doesn't deny, but rather shows the pagans worship the same: "As for him who affirms that we are "the priesthood of a cross," we shall claim him as our co-religionist. A cross is, in its material, a sign of wood; amongst yourselves also the object of worship is a wooden figure. Only, whilst with you the figure is a human one, with us the wood is its own figure. Never mind for the present what is the shape, provided the material is the same: the form, too, is of no importance, if so be it be the actual body of a god..."
Earlier, Marcus Cornelius Fronto (c. 100–170), the tutor of Marcus Aurelius, gave an anti-Christian oration c. 161, fragments which were incorporated within the century in the apology of Minucius Felix. Among the charges against the Christians, Fronto rants
I hear that they adore the head of an ass, that basest of creatures, consecrated by I know not what silly persuasion,--a worthy and appropriate religion for such manners. Some say that they worship the virilia of their pontiff and priest, and adore the nature, as it were, of their common parent. I know not whether these things are false; certainly suspicion is applicable to secret and nocturnal rites; and he who explains their ceremonies by reference to a man punished by extreme suffering for his wickedness, and to the deadly wood of the cross, appropriates fitting altars for reprobate and wicked men, that they may worship what they deserve...I purposely pass over many things, for those that I have mentioned are already too many; and that all these, or the greater part of them, are true, the obscurity of their vile religion declares. For why do they endeavour with such pains to conceal and to cloak whatever they worship, since honourable things always rejoice in publicity, while crimes are kept secret? Why have they no altars, no temples, no acknowledged images? Why do they never speak openly, never congregate freely, unless for the reason that what they adore and conceal is either worthy of punishment, or something to be ashamed of? http://www.earlychristianwritings.com/text/octavius.html
Although murky, it does become clear, seeing the association of "ass-worship" (which the Christians, and Jews, denied) and the Cross (which the Christians did not deny), that Christian worship involved more than just ideas.