Without modern medical knowledge, there were many assumptions about what caused the plague, covering everything from divine punishment to Jewish people poisoning the wells. There was a lot of persecution that occurred during the plague, and deaths that resulted from biased beliefs. Individuals with something as common and basic as acne were often put to death for fear that they were the source of the plague or causing it to spread.
The Europeans were so desperate to avoid the plague that many people gave all of their possessions to the church hoping to buy forgiveness and reprieve from the illness. This of course did nothing to save anyone from the plague and left the church very rich in the end.
There were extremes in both people's religious repentance and attempt to save themselves through the church and those who turned away from the church and to more lewd acts. Flagellants went from city to city where they would flog themselves for a set time period then move on to another city. This was an attempt by these people to purify themselves and help purify the cities they visited. They did not do this without doing something for themselves as well. In order for them to perform their services, the people wishing help had to pay a fee.