At the time of the plague, the Catholic church dominated every state politically; they were the undisputed masters of Europe.
After the plague, they never recovered the same amount of control again. This was the start of a long decline that continues to this day. The plague revealed how truly ineffectual and predatory the church was, even to the most ignorant.
Recommend the books The Black Death and The Dancing Plague, I'm over simplifying of course there are many other details.