Why was the role of any religion so important in medieval society?

In the Middle Ages, a monarchy was established in many countries. The clergy were a privileged class, whose duties included only service in the church throughout their lives. At the same time, representatives of this class were exempted from paying taxes. For this, the rulers demanded the support of the authorities. Representatives of the clergy carried out propaganda among the common population that the ruler was God’s chosen one, his decrees must be carried out. This allowed the state to gain support among the population. Also, at that time, no scientific discoveries were made, the perception of people was based on the fact that nature is higher than man, that it should be worshiped.