I don't doubt that the word has different meanings in other contexts, but the one that you point out is very usual here in Brazil. It is used mainly by Spiritists (Animists) who do not want to be perceived as representatives of the organized Kardecist movement. In that sense, it is a claim of noncommitment, not much unlike "Spiritual" itself relates to religion.
However, I get the sense that the OP is not talking about animism and/or Spiritualism at all,
@loverofhumanity .
In practice, both "Spiritualist" and "Spiritual" strike me as code words requesting the interlocutors not to be too questioning and to keep the conversation at levels and matters that do not invite confrontation. "Spiritualist" presumes an animist bent and, usually, a belief or even a definite interest in mediunic phenomena, while "Spiritual" tends to hint at a lack of such animism and at a general, perhaps unfocused theistic belief.
I guess that is fair enough. But it is also slightly frustrating. Ironically, the net effect is that I end up perceiving both groups as uninterested in true religious matters.