What would happen to me if I preached that the Eucharist (communion) is just a symbolic act and not literally Jesus' flesh and blood, during the Middle Ages?
Would I get burned to death?
There was a knight who did this and he got excommunicated
He was the first person in history to do so.
He later recanted his views and died in good standing with the church though
Depending on how charasmatic you are i think. If not important the Church will probably just tell you why you are wrong and maybe kill you if you continue. Probably likelier a mob killsyoufor it.