The Christian Church, effectively the Church of Rome (though other churches existed), was the most powerful organization in Europe, prior to the Great Schism of 1054. After that, the Roman Catholic Church took that power in the West, and the Eastern Orthodox took it in the East.
The Church, in any case, was regarded by most people as the only route to salvation. Most people were probably very much in fear of damnation in Hell for all eternity. The Church provided guidance, discipline, and, to a large measure, support. The church started children off on the road to salvation by baptizing them, and it provided marriages and funerals, and anointed the sick, along with other sacrament's.
The Church had organizations to help the poor, protect travellers, especially pilgrims, and even intercede in disputes. A person who needed to hide, whether a battered spouse or a queen on the run for political reasons, or even sometimes a fugitive criminal, could often do so in a monastery or convent.
The Church had penalties it could use to influence even the most powerful kings and emperors. If the Church excommunicated a king, it often meant that the people who had sworn oaths of allegiance to him were freed of those oaths, and other kings were given licence to invade that king's country. Very few kings were interested in trying out what it was like to be excommunicated.
The Catholic Church
The Roman catholic church during the middle ages in Europe can best be described as a church that was a stable influence. This was during a time where central governments were weaker.
"indulgences".
The practice of indulgences began in the Catholic Church during the Middle Ages, around the 11th century.
the Roman Catholic Church.
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The Catholic Church denies things that it hasn't done.
Roman Catholic Church
They were and still are the head of the catholic church
Protestant churches had barely begun during the Middle Ages. The most powerful Church was the orthodox Christian Church. At the Great Schism, it separated into the Roman Catholic Church, which was arguably the larger, and the Eastern Orthodox Church. From a time before the fall of the Roman Empire, there were always also other, smaller church organizations, such as the Coptic Orthodox and Oriental Orthodox Churches.
The Protestants left the Roman Catholic Church after the Middle Ages ended, during the Renaissance.
The Catholic Church