Too many things going on in the movie.
Basically a kid kills another kid with extra teeth, church fomented it, another kid dies after being tripped by the extra teeth kid and dropping a host at mass (felt guilty about dropping the host - Priest stops mass because of it), kid with extra teeth tells kid that eventually kills him (and friend of dropping host kid) how to bring him back etc. Oh ya, the kid with extra teeth supposedly bit his baby sister to death in her crib. Not true per the Mother angry about her kid with teeth being murdered and a supporter of current Italian Gov and turns against them.
Superstition that kid with teeth byproduct of in essence bestiality involving a pig therefore must have been the Devil in rural religious superstitious Italy of the1950's.
Meanwhile, because the church involved DC Gov of the time wants it investigated (extra teeth kids Mother the reason), sends its Rep down that tries to figure out what in God's name happened - Mission Impossible per my 1st two paragraphs, gets way too involved and in the end I'm certain he wished he had stayed in Rome and pursued some nurse looking after his Father in a home (and what did that side story have anything to do with the core plot?).
Too busy and weird (the pig thing was deranged to me - ya, they killed it for eating the host). Not much horror. They call it Padano Gothic.
Shock for the sake of shock at times (the whole pig, host sideline story that comes with Mother Superior's involved).
Told you it was a busy movie.
I call it 6 stars for the effort and the investigator and kid murderer actors were decent as was kid with teeth. The rest more like filler if you ask me.