Isn’t manipulating and preying on the gullible the main way that religion causes harm?
Gulliblity isn’t binary. I’d argue that those buying into organized religion are more gullible than people who identify as “spiritual.” If I asked you to rank people from least to most gullible based only on their religion, would you not rank a person that considers themselves spiritual but not drawn to a particular church higher than a member of a pentecostal church that regularly attends faith healing events?
Finally, this part is anecdotal but, the majority of people I know that consider themselves spiritual but not religious are people that attended one or more churches for a while but questioned or took issues with parts of those churches teachings. They may believe that there is some form sky daddy watching over us but, by they have displayed a degree of critical thinking. I can’t present concrete proof that sky daddy isn’t real so, as long as they aren’t using that belief to cause harm, I see no reason to immediately distrust someone simply for considering themselves spiritual.