As in so many areas of life, Americans in the 1960s questioned past religious practices and searched for authenticity or genuineness in their spiritual experiences, whether in established faiths or in new religious groups that formed as cults or communes. A cult is a group of people who share the same beliefs but whose beliefs and lifestyle are unlike the majority's beliefs; a commune is a group of people who live together cooperatively, sharing work and expenses. Moderate Protestant churches, long the bedrock of American religion, saw declines in membership, while membership increased in smaller, theologically more conservative Protestant sects, with their more fervent and expressive forms of worship. The other mainstream religions—Catholicism and Judaism—also experienced important changes. The Catholic Church modernized some of its key doctrines and...