Reply #33: If you go to the full study, you find that the abstract is missing a key point.

[More Than A Feeling]

With respect to religious characteristics, physicians who were more likely to practice in underserved communities included those with high spirituality, those who strongly agreed that their religious beliefs influenced their practice of medicine, those with no religious affiliation, and those who grew up in families that strongly emphasized service to the poor. Physicians who were more religious in general (as measured by intrinsic religiosity or frequency of attendance at religious services) were not more likely to report care for the underserved, nor were those who viewed the practice of medicine as a calling.(emphasis added)

http://www.annfammed.org/cgi/content/full/5/4/353?ijkey=0920a2417c35a96bd90e02e9e746abbf8da17a09#SEC3

That's where they got the line about atheists, agnostics, and the non-religious.