The explanation that is most commonly given for this is that the original Puritan settlers of New England were the most radical of the Puritans. Therefore, it was practically inevitable that religious fervor would decrease in later generations. The original settlers were people who felt strongly enough about their religion to leave England. They did so in a time when Puritans were somewhat persecuted in England. Therefore, they had a great deal of religious zeal. Their offspring had much different lives. They did not grow up persecuted for their religion. By the 1660s, the English Civil War was over and Puritans were not persecuted. In short, there was little to instill in the younger generations a true religious zeal.