Those people were called Reformers. The Reformers most famous today are Martin Luther and John Calvin. Luther alone posted 95 objections against Roman Catholic church practices and Calvin wrote several books on the subject, so you don't want me to go into great detail here.
Their main objection was that Christian belief should be based directly on what it says in The Bible, and not on what the Pope, bishops and priests gave you as their interpretation of The Bible (the art of printing just having been invented, most people never had seen a bible up close, let alone read it themselves). They objected also against many rules and teachings of the Roman Catholic church that had no basis at all in the Bible itself, like the existence and worshipping of the Saints and the Holy Virgin, the power of bishops and priests over the faithful and - especially in the case of Luther - celibacy of priests.
To restore laws and to have social order in the church.
Some religious people wanted to reform the church during Medieval times because they felt the church was corrupt. There were several reform movements.
The church had the most power in the middle ages because it was the one thing that united people.
The Church
By going to church
St Teresa of Avila was a Spanish nun who coined the term "mental illness". Since during the middle ages the clergy were the ones to take care of the mentally ill, her discovery gave the church a little bit more understanding as to what they were helping people with.
The king and the Church.
the desire to eliminate wealth and corruption from the church
with alms and stuff
The church had the most power in the middle ages because it was the one thing that united people.
The Church
By going to church
The Catholic church was the "state" and ruled the society of the middle ages.
They had power over people, gave people hope and helped them
St Teresa of Avila was a Spanish nun who coined the term "mental illness". Since during the middle ages the clergy were the ones to take care of the mentally ill, her discovery gave the church a little bit more understanding as to what they were helping people with.
The only church in the Middle Ages was the Catholic Church. I am not sure what the question is asking about the church.
The Roman Catholic Church
The king and the Church.
The Catholic Church and the monarchy of Europe.