The problem with horrible things is that they are often made up of a bunch of sensible individual decisions.
Converting the biblical texts into a biological format, sure I can see the logic in that. Looking at that new living data and wondering how it could be absorbed by a host? Well, I’m sure that initially they figured it would be a way for volunteers to miraculous improve their biblical knowledge. Maybe a panacea for older priests who were having trouble with their memory. Something benign, not something sinister, not a method of indoctrination through injections or ingestion.
Atheists don’t really believe that religious folks are dangerously unhinged or anything like that. Just misguided but well meaning. And that’s why we refuse to believe that the parasitic worm that carried that biblical knowledge was intended to be harmful. It was probably seen as a symbiotic relationship by the scientific priest who worked on it.
How the worm got out of the lab and into the food supplies of the local avian population is a mystery. Likely some samples were sent to the compost instead of the incinerator. And thus, the psalm birds emerged.
The parasite took up residence inside the bird and following some latent instruction to pass on the information, took control of the syrinx. This resulted in the psalm birds we all know, singing psalms and holy verses instead of their traditional calls.