To Mulligan's charge in Telemachus that Stephen killed his mother, Stephen replies, “Someone killed her.” This exchange initiates a thread that runs throughout the novel. If God is to be understood as a creator who brings life into the world, he should also be understood as a butcher who takes it away.
Stephen is, it seems, capable of scientific thinking. In Circe he responds directly and reasonably to Mulligan's cruel remark: “They say I killed you, mother. He offended your memory. Cancer did it, not I. Destiny.” But as a metaphysician he cannot accept the shallow Christian view of God's unalloyed goodness. In Scylla and Charybdis he refers to a deity “whom the most Roman of catholics call dio boia, hangman god,” which Gifford notes is "a common Roman expression for the force that frustrates human hopes and destinies." This god is a quite literally a "butcher."
Bloom too thinks, in Lestrygonians, that “God wants blood victim.” That is, after all, the whole logic of the Incarnation, the crucifixion, the Last Supper. The YMCA throwaway that he is reading asks, "Are you saved?" and it describes the immersion by which we can be saved: "All are washed in the blood of the lamb."
In Oxen of the Sun a narrative voice modeled on the scientific writing of Thomas Henry Huxley attacks Stephen's "perverted transcendentalism" and refers contemptuously to his remark "that an omnivorous being which can masticate, deglute, digest and apparently pass through the ordinary channel with pluterperfect imperturbability such multifarious aliments as cancrenous females emaciated by parturition, corpulent professional gentlemen, not to speak of jaundiced politicians and chlorotic nuns, might possibly find gastric relief in an innocent collation of staggering bob, reveals as nought else could and in a very unsavoury light the tendency above alluded to."
In other words God, in Stephen's highly "unsavoury" view, is an omnivore who chews through every variety of human meat, pausing occasionally to cleanse his palate with the delicate juices of "staggering bob." The narrator pauses to gloss this last dish: "For the enlightenment of those who are not so intimately acquainted with the minutiae of the municipal abattoir as this morbidminded esthete and embryo philosopher who for all his overweening bumptiousness in things scientific can scarcely distinguish an acid from an alkali prides himself on being, it should perhaps be stated that staggering bob in the vile parlance of our lowerclass licensed victuallers signifies the cookable and eatable flesh of a calf newly dropped from its mother." YHWH here transcends his familiar aspect of murderous senile delinquent and becomes a ravening, gluttonous, red-toothed carnivore.
All of this can be dismissed as the ravings of a tortured jack Catholic, but Stephen's fanciful metaphysics complement the scientific vision that pervades Ulysses: human life is lived in bodies, bodies are perishable meat, and no one knows what survives the grave. Bloom thinks along these lines throughout Hades, ignoring all the pious cant about the afterlife and focusing on the facts of life (worth holding onto) and death (not worth thinking about for very long).
Mulligan seconds his opinions in Telemachus: "You saw only your mother die. I see them pop off every day in the Mater and Richmond and cut up into tripes in the dissectingroom. It's a beastly thing and nothing else. It simply doesn't matter."
 A less materialist inspiration for Stephen's view of the deity may perhaps be found in the works of William Blake. Thorton cites a passage from A Vision of the Last Judgment: "Thinking as I do that the Creator of this World is a very Cruel Being, & being a Worshipper of Christ, I cannot help saying: 'the Son O how unlike the Father!' First God Almighty comes wit a Thump on the Head. Then Jesus Christ comes with a balm to heal it'" (28).