How did the church unite the people in time period 3 in western europe?

The Middle Ages were a period in Europe dating from the collapse of the Roman Empire in the West, around the 5th century. However, the fixing of dates for the beginning and end of the Middle Ages is arbitrary. According to the Norton Anthology, "Medieval social theory held that society was made up of three 'estates': the nobility, composed of a small hereditary aristocracy,...,the church, whose duty was to look after the spiritual welfare of that body, and everyone else

Hope This Helped