Why in the Middle Ages in Europe there was a period of stagnation in all areas of knowledge?

In general, the early period of the Middle Ages was not fruitful for scientific knowledge. At this time, religion was the priority. In European cities, the Inquisition was operating, which fought against dissidents and denying Catholic ideals. Scholars who rebelled against religious knowledge were tortured. They were often executed for spreading ideas that were contrary to biblical events and ordinances. For this reason, Galileo was executed. Knowledge that did not coincide with the church knowledge was destroyed. Religion was the main thing in the life of society.