A substantial number of Americans describe themselves as spiritual but not religious. The phrase is widely used and consistently misread as though it named a shared position.
The phrase separates two different things
In ordinary American usage, religious has come to point at institutions, membership and inherited authority, while spiritual points at inner experience and personal meaning.
That split is not universal. In many languages and traditions the two words are not opposed at all, and practice is assumed to be both communal and interior.
The American separation is historically recent, and it depends on a prior situation in which belonging to an institution was the default assumption about religious people.
It is a statement about institutions
People who adopt the phrase are usually declining membership, authority claims and doctrinal packages rather than declining belief in anything transcendent.
Surveys and interviews collected by researchers tend to find that the group includes former members of many traditions, people raised without any, and current occasional attenders.
Because the phrase describes what someone is not doing, it predicts very little about what they do believe or practice.
The practices behind it vary widely
Some who use the phrase meditate, some pray privately in the tradition they were raised in, some practice yoga, and some describe nature or music as their primary access point.
Others use it to mark a general openness without any regular practice attached, which is a different position wearing the same label.
Sorting the category by practice rather than by self-description produces groups that look almost nothing alike, which is why the label frustrates researchers.
Why the category grew
Formal membership in American congregations has declined over recent decades, while interest in meaning, ritual and contemplative practice has not disappeared with it.
The phrase gives people a way to report that combination honestly, rather than choosing between claiming a membership they no longer hold and calling themselves nonbelievers.
Its availability as a socially acceptable answer also affects how many people give it, since labels become more common once they exist.
What the debate about it concerns
Critics from within institutions argue that individual practice lacks the accountability, obligation and continuity that a community imposes on its members.
Those who use the phrase often reply that institutional belonging carries costs of its own, including commitments they cannot honestly make.
Both arguments are about what religion is for rather than about whether particular claims are true, which is why the exchange rarely resolves.
The phrase's own vagueness sustains the argument. Because it names a refusal rather than a position, each side can supply the content it expects and respond to that instead.