Spiritual but not religious

Please argue what it means to be spiritual but not religious.
Here are some sources to provide your discussion. I need a minimum of 5 academic, peer-reviewed sources total.

-Andie R. Alexander and Russell T. McCutcheon, Im Spiritual, But Not Religious, pp.97-112 in Stereotyping Religion
-Graham Harvey, If Spiritual But Not Religious People are Not Religious, What Difference do They Make? in Journal for the Study of Spirituality (pp.128-41)
-Donald Lopez, Belief pp.21-35 in Critical Terms for Religious Studies
-Sean McCloud, Religions are Belief Systems, pp.11-22 in Stereotyping Religion