Christianity is monotheistic religion with The Bible as their holy book. Their savior is Jesus and Christianity was originated in Jerusalem. The had 10 commandments which Is a code of law for Christians. The afterlife consisted of heaven and hell.
Impacts of Christianity in Europe
While the Roman Empire was being taken over, they were told to accept the people's god who were taking over the empire. The Christians didn't want to accept any other god but their own. The Christians were also accused of being cannibals for drinking the blood of Jesus and eating his flesh. Also know as red wine and bread. As the Christians refused to accept, they were mistreated and killed. They were fed to wild animals, forced to fight lions for entertainment, fed to dogs and used as human street lamps.
Middle Ages & Crusades
During this period of time The Church has all power. The church had all knowledge and was close to God and knew what God wanted so you had to listen to the church. The church told you, you had to follow certain rules in order to go to heaven and If you didn't follow those rules no heaven, you're going to hell (excommunication). The crusades was a period of time full of holy wars between the Christians and Islamic in Europe and middle east.
This was a time where the church becomes corrupt . A munk from Germany named Martin Luther was angry with the church. He knew what the bible really said and hated that the church has been lying about what it says. So in responses Martin Luther creates The 95 theses, 95 reasons why the church was corrupt.