In a well-known twist, what usually results from the illusory attempt to lead a pure and spiritual existence, free from material baseness, is an obsessive fantasizing about excreting, copulating, and other “lower” bodily functions.
For example, the more puritanical among the Sixteenth and Seventeenth Century Protestants were carrying on a long tradition of iconoclasm, one found in the biblical books, when they attempted to purify Christian rites of any material significance. The way they saw things, the Eucharist must be viewed as a spiritual remembrance which rendered the material bread and wine merely accidental or it would inevitably descend into gross and base literalism: the cannibalistic eating of the body of Christ. The nuanced Catholic conception of the symbol as something both present and physical, and yet absent and transcendent, got caricatured as gross materialism, via a fervant literalism that itself was responsible for creating the idol which it was criticising.
So John Milton, in On Christian Doctrine, warns that the Eucharist must be no more than an analogy for a spiritual process. The alternative, in Milton’s fantasy (although never conceived as such by his real rather than imaginary Catholic opponents), was idolatry and scatological obsession:
“if we eat his flesh it will not remain in us, but to speak candidly, after being digested in the stomach it will be at length excluded.”
(On Christian Doctine, 1.28; tr. in Maggie Kilgour, From Communion to Cannibalism)
Or, as Milton later caricatures the Catholic view, shuddering (with a secret delight?) to even think about it:
“when [Christ's body] has been driven through all the stomach’s filthy channels it shoots it out – one shudders even to mention it – into the latrine.”
(On Christian Doctine, 6.560; tr. in Maggie Kilgour, From Communion to Cannibalism)
We’ve got both sides of the debate here, so it’s fairly easy to work out that Milton is misrepresenting the symbolic Catholic view. Perversely, it is Milton himself who is grossly obsessing on the materiality of the Eucharist. As Maggie Kilgour comments:
“in his attack on Catholic materialism he cannot resist the temptation of dwelling obsessively on bodily images, especially those related to the ‘lowest’ functions of eating and excretion. His own dualistic definition of communion enables him to indulge in the materialist fantasies he is suppose to be denouncing by projecting them outside of himself onto another group that he then attacks.”
(From Communion to Cannibalism, 84)
By contrast, in Isaiah 44, we don’t get both sides of the depiction of Babylonian worship, but just the Jewish caricature of the foolishness of idol-worship. But as George Soares-Prabhu questions in his article, ”Laughing at Idols”: might there actually have been in Babylonian religion, behind this base caricature of idols, “visual theologies of great depth and power”?