In what way did Christianity and Islam undergo a major change during the Middle Ages?
Christianity was in the dark ages, the religion took it down an ugly road where the intellectual feared for their lives, the thinkers of christianity began to feel they needed a new way
Hence secularism was born in Europe Hence USA is a secular country not found on christian principles
Islam on the other hand thrived in the middle ages, the religion made science and thinkers welcome, hence Jews and Muslims had their golden age of Science and learning
Islam was the world leader in all categories of life for over 1000 years until ww1 european colonialism