1. This assumes that judges (priests) are honest and neutral to the case, and doesn't believe in the intervention of God themselves.<p>2. This assumes people innocent in this case won't be afraid God won't help them because of theirs other sins (and who is not a sinner?).<p>3. I don't think people were that much religious then. I mean - sexually medieval people wasn't more puritanical than we are, why should we assume they were believing  in God thah strong (to put hand in the fire etc).<p>4. How do we know ordeals worked? It's obvious that priests were describing their work in superlatives. And they were the most literate class then.