According to the early Christian Clement of Alexandria (Stromata 3.59.3), the second century Gnostic theologian Valentinus taught that Jesus did not evacuate any of his food. Because of his supreme self control, the food did not decay inside him.
The idea reflects two themes common among the Gnostics of those times: the self-control more often associated with sexual abstinence, and the debates about how human Jesus was.
To us it just seems absurd. To think of Jesus as supremely anally retentive is hardly to pay him a compliment. If he didn’t excrete like normal humans, did he eat like them? If he did, as the gospels seem to imply, did his waistline just expand and expand? Yet for all its absurdity it is easy to find Christians today with equally impractical beliefs. As an undergraduate I shared a flat with someone who insisted that anyone who receives Holy Communion once a day does not really need to eat anything else. I didn’t test his theory and as far as I know he didn’t either. And then there are all the preachers who tell you that if you give them money...
Many people feel that they are more spiritual, more devout, if they believe more unlikely miracles than anyone else believes. Of course it is nonsense: it means not that they are more willing to believe spiritual truths, but that they are more willing to disbelieve physical truths. Those who confuse the two may perhaps define the spiritual as the non-physical, or religious belief as belief in miracles; but these are modern dichotomies, imposed on Christianity mainly by atheists trying to exclude it from the real world.
Ideas like this turn religious belief into an interesting conversation piece, an unusual ornament on a mantelpiece. They attract the attention, they invite questions and jokes, and perhaps they give a sense of distinctive identity to the person possessing them; but they rarely contribute to our understanding of reality. To this extent I suspect that the modern versions are more artificial than the ancient ones. My flatmate knew about digestion; his belief about consecrated bread and wine was a deliberate counter-cultural challenge to normal understandings of bodily functions. No doubt it was motivated by his inner explorations of his religious beliefs, but he was prepared to articulate his theory, at least for a while.
Valentinus, on the other hand, lived in a society where Stoics, Middle Platonists, Jews and Christians explored and debated the dividing line between human and divine beings. The Christians among them applied a variety of divine concepts to Jesus. Some of them stood the test of time, others didn’t. Eventually Valentinus’ teaching got condemned as heretical by the ‘catholics’, who stressed the humanity of Jesus described by the disciples who had known his ministry in Galilee