I think TNG made it pretty clear those silly superstitions are a thing of the past. I doubt anyone on the Enterprise believes they have a "soul".
So..what exactly did that one guy project into Data when he possessed him in Season One?
And that's not even touching the numerous other similar eps that had a more sci-fi angle.
edit: In fact, after encountering numerous wonders to satiate
desires both subtle and gross....I seriously doubt more than a handful of Enterprise crew sit there smugly going..."Pttt. There's no such thing as a soul."