I think it can be a combination of God (or angels), the devil (or demons) or our own minds. The trick is to discern which one is operating at any one time.
But I’ll give my Catholic psychiatrist’s personal experience (I’ve related the same story before), rather than my own this time.
I’d told him about a couple of occasions where a “Voice” said something very clear to me, in relation to concerns I’d had, mainly about frustration with “vocation” and in another instance, a one-time infaturation with a young lady (the voice implied that I ought to forget it!). I’m absolutely certain that on both occasions (and a couple of others as well) that they definitely did not come from me. In addition I’m also pretty sure they came from God or an angel, and not an evil source.
The psychiatrist said, “That’s interesting. Did I tell you about my experience?”
He hadn’t, so he said he’d been working in his office typing on his computer, when a voice just said to him out of the blue, “Go to Maclean!” And that was it. No context, no preamble, not related to anything he was thinking about or doing - just a three word command, out of the blue, quite clear, and absolutely devoid of context.
He wasn’t even sure which Maclean the voice was referring to - Maclean in Northern New South Wales, North or South Maclean not far from where I live, or some other Maclean.
Anyyway he gets involved in “family healing masses” due to his deep spirituality and also his psychiatric insights. About two weeks after the voice in the office, he was at Lismore in Northern New South Wales, involved in one of these healing masses, when an aboriginal woman came up to him and said, “I don’t want to make a nuisance of myself, or cause trouble or anything, but I seem to be getting told you should go to Maclean.”
So here was the second part of the riddle. He went, and ended up on some river island where aboriginals used to be “locked up” in the early days of settlement. He said there was some unfinished spiritual business. In the long run however, he seemed to think it had more to do with the lady herself, who’d become a Christian, and needed a bit of support as she was having some trouble from her own people. Something like that.
So in his case, I think the voice, which was very clear, was from God, or an angel on behalf of God.
Where the confusion arises is when we are thinking about something, and a voice cuts in, telling us what we want to hear a lot of the time. In that case, I suspect it’s more often our own, or demonic. And that’s why we need to be careful.
I well remember my old Presbyterian / Methodist pastor, one of the wisest and most prophetic men I’ve met saying certain negative things to me, that I’d do this and that nasty thing in the future, etc. etc, when he suddenly stopped with a quizzical look on his face. “Hang on a minute”, he said, “I think the devil’s telling me all this!”
And he wasn’t often wrong. So if he could be fooled for a short while, we all can.
It’s a tricky area. But Paul wrote about the devil disguising himself as an angel of light nearly 2000 years ago, so what’s new? CS Lewis introduced one of his Ransom SF trilogy by way of a character enduring a “barrage” of fear inducing thoughts as he walked towards Ransom’s cottage on a dark night. My own opinion about that is that Lewis could write about it as fiction, because he’d experienced it himself as fact.
So there’s two great minds that experienced the same thing.
I would suggest…Don’t over think it! Just my 0.02