The result of the Khmelnytsky Uprising and the later wars in Poland that killed perhaps as many as half of the 200,000 Polish-Lithuanian Jews was a breakdown of Traditional Orthodoxy and a rise of mystical ones. It gave us the Hasidic movement as well as a swell of disorganized Messianic zeal that led to widespread acceptance of Shabatai Zvi and Jacob Frank. Reform Judaism is the opposite of this.Very interesting. I don't remember Paul Johnson covering this in the History of the Jews.
Where did you read about this?