For example many atheists are members of the Unitarian Universalists, Reform Judaism, Buddhists just to name a few, and they would consider themselves spiritual, in fact they might even be pegged as religious, since they attend services at these organizations. I have often met atheists outside these groups as well, who call themselves spiritual, though when I ask, it seems to be they define spiritual as anything to do with feelings and emotions or human interdependence, which would definitely not be the way I would define it, but on this survey we would have no way of knowing, and I was somewhat surprised by how many people define spiritual this way. This makes sense as society uses the term spirit in a way that is not god oriented, for example team spirit, playing with spirit, are phrases that are talking about emotions and motivation, and group interaction, not the supernatural.
Here's just one example
http://spiritualhumanist.blogspot.com/So it would be difficult to tell what is up with this study, unless they had specifically shown the results on atheism and agnosticism, which they didn't, though it seems they could have. Also in the religiosity criteria, those with low religiosity, would include other besides atheists and agnostics, so it is pretty meaningless category to try to determine anything about atheists. For example 394 respondents had low religiosity, but only 110 had atheist, agnostic or none as a religious affiliation, and even many atheist Jews and Unitarians would probably end up ranking high in religiosity, which is a criteria the researchers made up themselves based on other questions, such as service attendance, I know many atheist Jews who are very active in their Reform Temples.
Also you missed a critical part, were they evaluated these criteria by religious affiliation, they looked at those who had a religious affiliation(.7) and excluded all that didn't meet other criteria that had ranked higher in correlation by themselves, that is high religiosity(1.1), and families who strongly emphasized serving the poor(1.7) yet:
"Combining religious characteristics and measures of motivation had little effect on practice among the underserved. For example, among the subset of physicians from all specialties who reported a religious affiliation, had high intrinsic religiosity, attended religious services twice a month or more, and grew up in families that emphasized serving those with fewer resources (n = 264), 90% agreed that their religious beliefs influenced their practice of medicine, and 86% viewed their practice of medicine as a calling. The proportion who reported practice among the underserved (31%) did not differ significantly from that found among those with no religious affiliation, however (35%, P = .48)."
Since taking religious affiliation and removing most of those who would have ranked low by their various answers to other questions, we would have assumed that these would then easily beat those without any religious affiliation but they did not, in fact those with no religious affiliation alone as a criteria still beat them by a small amount. This actually means, by the way that many who classified themselves as atheist, agnostic and none, must have to a decent percentage, classifying themselves as spiritual, which is not surprising if you know how many atheists, agnostics and areligious define the word spiritual.
If we look at actual religious denomination, the results were
Catholic .7 Jewish .3 Protestant .7 Other Religion 1.0 None 1.0
The none category included people who reported as atheists, agnostics and none. We can see that Judeo-Christian affiliation did pretty poorly. Even if we take the better results from "other religion", we would still end up with religious affiliation at about .7 and No religious affiliation at 1.0, It's only by adding exclusionary criteria to those with religious affiliations that we can even get them close to the non-religious.
You are right that the article is mis-titled, a better title would have been "Judeo-Christian religious affiliation not linked to helping the poor in Mediicine".