The money quote:
The reason (I surmise) that so many people claim to be spiritual rather than religious is that being spiritual imposes no discipline upon them, at least none that they do not choose themselves. Being religious, on the other hand, implies an obligation to observe rules and rituals that may interfere awkwardly with daily life. Being spiritual-but-not-religious gives you that warm, inner feeling, a bit like whiskey on a cold day, and reassures you that there is more to life—or, at least, to your life—than meets the eye, without actually having to interrupt the flux of everyday existence. It is the gratification of religion without the inconvenience of religion. Unfortunately, like many highly diluted solutions, it has no taste.