Replying to: "In the seventeenth century, some Europeans even considered them to have been created by the devil."
Almost all pre-modern societies considered disease and sickness to be caused by evil spirit or power. The germ theory of disease was not proven until barely 150 years ago; and until the last few decades there still many places of the world where the germ theory was held in suspicion if not outright disbelief.
A mushroom which looks exactly like another mushroom but kills you is surely the work of malevolent spirits or evil people calling on these dark powers.