When Wade Clark Roof published his influential book on baby boomers and religion six years ago, he found that the post-World War II generation was not just looking to change the way it worships, but was changing the way worship looks.
In the 1993 ''A Generation of Seekers,'' the University of California-Santa Barbara religion professor explored how boomers built their own beliefs in a higher power, mounting journeys through a variety of faiths, cults and New Age practices to find what some called a custom-made God.
The generation that broke down traditional morality in the secular world of the 1960s and 1970s had also moved away from traditional religion in the spiritual world. Their parents found the changes threatening and worried they heralded a general weakening of the cornerstones of society.
Returning to the subject in a new book, ''Spiritual Marketplace,'' Roof finds boomers are now surer about their beliefs.
''They have a more mature religion,'' the 60-year-old Roof said in an interview. ''They have a better sense of what they believe in and experience stronger commitments than they did before.''
In the new book, he writes, ''Identity is still a powerful theme, but its mode of expression is now different: The energizing forces arise out of quests not so much for group identity or social location as for an authentic inner life...''
Roof's latest research has found many subtle changes in boomers' beliefs and practices since his 1993 work.
Back then, he found boomers weren't walking away from God, just from church as they had known it, to pursue a personal journey. His research, surveys and interviews, conducted between 1988 and 1990, showed that most who strayed from church did not become atheists.
Instead, they believed in a God who was more down-to-earth. Christians believed in a Jesus who wasn't necessarily the sole savior of the world.
For his new book, Roof went back to reinterview some of those he talked to before. ''They are a more settled generation now,'' Roof said, and their beliefs are more pluralistic.
The boomers' religious landscape, according to Roof, no longer traces its borders along denominational lines of Jew, Protestant, Catholic. Instead, the lines run along categories that describe how belief affects people's lives: dogmatists, born-again Christians, mainstream believers, metaphysical believers and seekers, and secularists.
For example, dogmatists are reacting to what they perceive as the moral relativism of modern life, trying to get back to a time when right and wrong were less subjective. Metaphysical believers follow in a tradition set in the 19th century, when the turmoil of a changing economy prompted people to join Transcendentalist and Revivalist movements.
Roof found that as many boomers age, they are going back to churches they once left. That does not mean they are renouncing beliefs they picked up along the way.
''This generation is remarkably capable of fitting many things together,'' Roof said. ''They can draw from many sources, but there tends to be a core. Even if they draw from pop psychology, they still build it around their core Jewish faith or core Christian faith.''
Even if a person is a Christian, he or she finds much to be learned from, say, Buddhism, Roof said. ''You get these constellations that are somewhat diverse in terms of religious practices,'' Roof said.
He said they express more certainty in their beliefs. Having returned to church or synagogue, they have stayed, tailoring the religion's traditions to their needs.
''There is considerable fluidity,'' he said. ''They're a very mobile generation in terms of what they think. There's a continuing hunger to find spiritual truth, but they have a clearer sense now that some of the things they looked to deliver them earlier, like consumption and materialism, don't work too well.''
Whereas they were willing to try many things earlier to reach fulfillment, now they are staying closer to the tried and true.
''There is a turning away from the esoteric and highly popular latest fad ... to a more serious level of reflection,'' he said.
When he wrote the first book, Roof said, he found many boomers returning to church for the sake of the children they were raising. They wanted the children to have a strong grounding and set of beliefs. But as those children have grown, their parents have become more lax in their churchgoing, viewing child rearing as a phase during which they are supposed to pass down their traditions.
Roof said he believes boomers will continue to shape religion and belief as the century turns.
''I don't see a secular future,'' he said. ''I see a more diverse, perhaps more individualistic religious and spiritual future ... These quests have led to a heightened spiritual sensitivity on the part of this generation that been through so much.''