For reference, around 30% of Americans consider themselves "Spiritual but not religious." (source)Another [BYU] professor reported something that intrigued me greatly. He said that when LDS young people drop out of the church, they give up religion altogether, and they don’t join the ranks of the "SBNR" – spiritual but not religious. Perhaps Mormonism is such an all-consuming experience that its people see it in all-or-nothing terms. (source)
I've definitely seen this tendency in my own friends and family members who no longer consider themselves Mormon. A few of them attended Unitarian services for a while, but didn't continue, although one is now loosely affiliated with Quakerism.
I don't have statistics on how many ex-Catholics, ex-Episcopalians, etc. become SNBRs, but Dr. Burklo's reaction above implies that it's more common in other faith traditions (or that he's surprised it's uncommon for Mormons for some other reason).
Anyway, I'm curious to hear why you think this is the case (or hear your personal experiences if you're one of the above). Do you agree with Dr. Burklo's guess that it's an "all or nothing" issue?