I've been reflecting about why it is that I'm somewhat sceptical about a literal interpretation of mediumship. I think it may have something to do with free will. We are instantiated into this world as beings with perceptions which I see as limited. We perceive what are apparently separate objects, either animate or inanimate, and have an intrinsic need to explain what it all means and how all these apparent objects interrelate.
There's no shortage of explanations -- in the past, religions played a major part in providing them, but these days, it's mostly science, at least in the West. All our explanations are at best only approximations of the truth, whatever that might be. As a species we are constantly trying to refine our understandings. It's good that science has a more prominent role to play than formerly, though I think recently it's been tending more towards scientism, back towards a kind of religiosity rather than a spirit of true enquiry.
By and large, most people just negotiate the apparently brute fact of the world as best they can. They may mostly experience it in a "non-spiritual" way, and nothing stops them from interpreting the world in any way they choose. Even in the most repressive regimes, no one can monitor their inner thoughts. No one can censor what they believe if they choose to remain silent about their interpretations: our thoughts, opinions and motivations remain private if we choose not to divulge them.
Nothing stops us from behaving in any way we wish except practical impositions (such as man-made laws, etc.), but even if those are extreme, nothing can prevent us from at least thinking as we wish. There is always free will in that sense. God (I prefer the term MAL or Mind-At-Large) doesn't seem to be interfering with that freedom, always of course within the framework of the perceptions and their interpretations that we were either instantiated into and/or have been influenced by others into accepting.
If we are to believe that mediums possess a special ability to relay messages from spirit entities which aren't currently earthbound, then it seems that MAL left a back door open through which our free will decisions can be influenced. Now, I'm not saying that there aren't spiritual experiences that we may have in our lives; I've had a few myself, albeit not of the psi flavour. The question for me is about from whence they come. If they originate external to our innermost selves, then we aren't completely free; there's an element of determinism in the system over and above the practical constraints that being instantiated or incarnated can't help but place on us.
I have this tendency to reject the idea that MAL leaves us breadcrumb trails; indeed, that it interferes in any way with our evolution; being human means that we have to accept the responsibility for our own evolution. Which sort of implies that MAL really isn't external to us; it's within us all the time, experiencing along with us. In fact, we aren't distinct from it.
To my way of thinking, we are what MAL becomes when it restricts itself by identifying with one of its many dissociated alters. In fact, I once experienced what I now interpret in this way; it may sound egotistical, but I was aware of being something much grander than I usually perceive myself to be. Most of the time, I'm pegged at a significantly lower level, engaged by everyday concerns and general humdrum. I forget what I am and what others are; maybe that's what blasphemy truly is: not constantly being aware of what we truly are.
When our bodies "die", we may become more (not necessarily completely) aware of what we really are. We may be more identified with MAL. Now: being closer to the one MAL, do we then seek to interfere with the progression of "others", or do we, on the contrary, leave it to "them" to have the chance of experiencing unaided something of their own grandeur? It's an immensely pleasurable experience, I found: what's the point of trying to nudge people towards it and denying them that pleasure of self-discovery?
Maybe the aim is for everyone to be present in this awareness all of the time; when we are, we can evolve further, whatever that means. If people gradually become more aware of what they truly are, I have no doubt that, as then presently incarnated, they can influence others simply through their being what they are. No need for them to try to do so from their "spirit" form.
I once came across a bloke back in the mid-eighties who greatly affected me by his mere presence. He was a market trader -- his appearance was nondescript; he was possibly Indian or Pakistani. I was standing with a friend at a nearby stall perusing goods when a woman came up to his stall to show him a defective item of clothing she'd purchased.
All he said to her was something like: "Oh, that's alright, love. Do you want me to exchange it, or return your money?", but he said it in such an utterly sincere and welcoming way. My friend picked up on it too. Later I resolved to go back and find him, but I never could. Maybe he went on to trade at a market in some other town. I'd give anything to hear him speak again -- needn't be about anything earth-shattering; could be about the weather, or the price of fish for that matter. It is the sincerity and openness I want to be in the presence of again.
Idries Shah speaks of something similar: as I recall, it was about a man who was preparing kebabs to sell, or something like that. A seeker saw him and was instantly transported into an ecstasy. It's possible we all have the potential to become like the market trader or the kebab-seller; that we all have the potential to communicate directly our grandeur, without necessarily even using words.
Anyway, that's what I wanted to say. My opinion about mediumship is influenced by who I am and what experiences I've had. I may or may not be correct, but I do have reasons for thinking the way I do: it isn't arbitrary.