The very reverse is true. "Spiritual" without "religious" is soo woosie, vague and indeterminate, and always amounts to self-congratulation and eventually decays into smug narcissism (my story). It is naive about the human capacity for self-deception, and how easily we rationalise our appetites to do what we want anyway. It is intellectually lazy, because it fails to engage seriously just what is meant by "spirit" or "truth" or "life". It avoids personally engaging the deep questions about the architecture of the universe, especially the moral universe, and remains agnostic and ultimately uncommitted about right and wrong, good and bad, truth and untruth, reality and unreality. Real religion makes real demands (and yes, there are many counterfeit religions). Real religion, like life itself, demands real relationship with more than a vague sense of something spiritual. The word itself denotes a commitment, a bond, an attachment (ie a relationship) and like real life, it is filled with drama and dogma and cult, something those who only live on the periphery cannot understand or even desire (like me, for many years). I thank Almighty God I eventually emerged from my atheistic slumbers in which I smugly reposed for so long. As Antony Flew (the world's foremost academic atheist for many years) eventually discovered, atheism is not intellectually defensible. So where to start? Plato and Aristotle. Especially Aristotle.
PS: Of course I expect to be flamed, mocked and derided. Just don't pretend it's in the name of tolerance.