To clarify, according to Pew it is both true that organized religion is losing people
and that the population of atheists is growing
but that doesn't mean that saying "Losing its Religion-Americans becoming less Christian and More Atheist" presumes that the "Unaffiliated with organized religion and "atheist" are
not at all
the same thing", though the proximity ( of "Less Christian and More Atheist") in the OP statement might have been unfortunate.
Certainly someone can be atheist (sans a belief of deity) who might be otherwise spiritual just not into the God thang--there are many spiritualists (even so-called mediums) who consider themselves atheists--so the statement in the OP is true in both its parts, just badly worded.