The Religion News Service column “Flunking Sainthood,” as the title indicates, expresses the outlook of liberal Latter-day Saints. But author Jana Riess, who comes armed with a Columbia University doctorate in U.S. religious history, is also interesting when writing about broader matters.

Her latest opus contends that two standard theories about big trends in American religion are too simple and therefore misleading. Her focus is the rise of religiously unaffiliated “nones” to constitute 39 percent of “millennials” from ages 18 to 29. The Religion Guy more or less agrees with her points but adds certain elements to the argument.

So, theory No. 1: Though Riess doesn’t note this, this concept was pretty much the creation of the inimitable Dean M. Kelley (1927–1997) in “Why Conservative Churches Are Growing.” This 1972 book was electrifying because Kelley was a “mainline” United Methodist and prominent executive with the certifiably liberal National Council of Churches. (His expertise on religious liberty gave the NCC of that era a major role on such issues.) 

Under this “strict churches” theory, religious bodies that expect strong commitments on doctrine and lifestyle from their adherents will prosper because this shows they take their faith seriously, and  they carefully tend to individual members’ spiritual needs. By contrast, losses characterize more latitudinarian (Don’t you love that word?) denominations such as those that dominated in the NCC.

Kelley’s scenario proved keenly prescient, since white “mainline” and liberal Protestant groups were then just beginning decades of unprecedented and inexorable declines in active membership and over-all vitality. The Episcopal Church, for one example, reported 3,217,365 members in 1971 compared with 1,951,907 as of 2010. So much for left-wing Bishop Jack Spong’s 1999 book “Why Christianity Must Change or Die.” Statistics have been even more devastating with groups like the United Church of Christ and the Church of Christ (Disciples).

Now comes Riess to announce that scenario is “crumbling” because some strict conservative groups like the Southern Baptist Convention (SBC) have also begun declining in recent years while others, e.g. her own Latter-day Saints (LDS) or Mormon Church, still grow but at more sluggish rates.

That’s accurate, important, and yes it tells us factors other than strictness are at play. But analysts still need to ponder why the SBC grew steadily through decades of internal turmoil until the early 21st Century and why Mormonism and certain evangelical Protestant groups continue to defy seculr inroads to expand. There is also a difference between decline and implosion.

Theory No. 2 is the “political alienation” theory, which says younger Americans are turned off by the alliance of many conservative Christians with conservative politics, which became more visible in 1979 when the now-defunct Moral Majority was founded and activists launched the SBC’s rightward swing. 

Indeed, polls show numerous young adults are liberal, especially on LGBTQ issues, and hostile toward Republican President Donald Trump.

However, as Riess correctly notes, if this fully explained matters then young “millennials” dissatisfied with conservative congregations would be switching into liberal and LGBT-affirming churches -- which they are not. (For that matter, some conservatives doubtless drifted from churches over their liberal politics but there was no mass exodus.)

So, then, why are 39 percent of Americans under 30 unaffiliated?  Riess’s explanations:

* Marriage has much to do with fostering church involvement but many of today’s Millennials are marrying at later ages or don’t even bother with marriage. (Riess does not mention the sad fact that suicide now roughly equals homicide as a cause of death and singles are several times more likely to take their own lives than married Americans.)  

* Related to that, lower rates of child-bearing weaken ties with religion. This has been crucial, for example, among Southern Baptists.

* “The ‘nones’ are growing because the ‘nones’ are growing!” A circular argument, Riess admits, but her point is that once church affiliation is not a widespread social expectation the trend reinforces itself and encourages vaguely nominal members to drop out.

The Religion Guy would add at least three more factors:

* Since the 1960s, younger Americans are more skeptical toward established institutions of all sorts or unwilling to make commitments to them, which of course includes conventional religious congregations. Non-religious service organizations similarly scramble for volunteers these days.

* The rise of social-media devices encourages restricted electronic relationships as opposed to actual face-to-face interaction with other people, which still characterizes local religious congregations and used to be seen as a benefit of belonging. We’ll see much more of this.

* People expect a high moral standard of religious bodies -- rightly so -- and  specific scandals and missteps in recent decades have generally damaged the appeal of all faiths.

Other suggestions?