I tend to find that those who claim that they are spiritual, but not religious, are really neither. How can you meditate on a spirit when you have no religion to base it on? What do they ponder, clouds, streetsweepers?
Speaking as someone who suffered from aridity of spirit for nearly a decade, I held to my religion, knowing my spirit would fall into line when the time came. Without religion, how is this possible? Gosh, how do you even know what “spiritual” is?
In my opinion, this is an irrational position. One cannot acknowledge a spirit and have nothing to base it on. It is like saying I am intellectual but never study. If I am in the Church, I can commune with the God of Faith, even if only mentally. But outside of it, with no guide, even this is not possible. The only possible thing you can venerate is personal emotion, which is not spiritual at all. I guess they could be emotionalists.