In the eyes of his creator, this recreation of life in the form of the monster is a truly amazing and wondrous thing. This breakthrough will mean a great deal to mankind. However to the inhabitants of the village wherein the castle is located, the monster poses a terrible threat. There is an existing communal order, and as a part of that ethos, the villagers all believe that dead people are supposed to remain dead. A new order has been introduced into the world and the natural reaction to a change in the world takes over.
People grow fearful of the unknown.
If you recall the monster, he actually had a quiet and peaceful side. Fast forward to the next scene. I see the leaders of the village whipping up their neighbors into a fit of frenzy. I see the villagers roaming through the streets carrying torches, and poking into every crevice in their hunt for the monster. And imagine how scared the monster becomes when confronted with the burning torches of the villagers.