Okay, how do we get to the knowledge about, say, Ahriman. From a current layman standpoint, the existence of some malicious spiritual being may be ridiculous. So how can we get a little bit more sure about it.

I’ll try to trace back the steps what is needed for this knowledge.

One step back is the existence of spiritual beings in the first place; be it God, gods, angels, elemental beings, ghosts, spirit guardians, or demons and devils.
If you have experience with one of these, the others may be close at hand.

Experience is the key, I now reckon. Pure logical it might not be possible, or very hard, otherwise Rudolf Steiner’s Philosophy of freedom wouldn’t be so obscure outside the anthroposophy.

What comes before spiritual beings. The spiritual world itself, that there’s a spiritual world besides and intertwined with our world. Even natural science, and/or mathematics is talking about other dimensions, multiple intertwined and curled up into each other.

The step before that is about energy, soul, spirit, aura, chakras. If you have a feeling or experience one of these exist, a whole separate world of it wouldn’t be so far fetched.

Before that? Hmmm. Things like ‘coincidences’? People thinking the same at the same time. Just thinking about someone just before they coincidentally call? ‘Weird’ ideas, sudden inspirations out of the blue that works out very well?

Or just the sense there’s ‘something’.

Where are you on this scale?