First best and truest answer to the titular question is: I do not know. That non-material, i.e. spiritual beings, are real is, in my mind, indisputable. So is whether they are active. They are. I know for a certain fact that I have interacted with non-material beings, beside God, and it is likely you have, too. Here is how this might work.
The argument I give today is no way conclusive. I tried looking up these ideas, which are surely not unique or original, but my ignorance on the technicalities of the subject is profound, and my search inadequate. At any rate, let’s push on!
Cast your mind back to Chapter 13 of the Summary Against Modern Thought. We learned that God must exist or no change or movement could take place. The link has the full details, but briefly they are this.
Right now—not in some distant past—but right here, right now, as you hit the scrollbar, the scrollbar moves. The muscles in your arm and hand flex. The chemicals in your hand and arm act and react to cause the flex. The electrons in the chemicals move in certain ways to cause the chemical interactions. Whatever is inside the electron changes state to cause the electron to move.
What is inside whatever is inside the electron again changes to cause the change “above” it. And so on. But not and so on ad infinitum. The process must terminate at some finite point. If it didn’t, no movement or change would ever occur. That finite termination point is God. God is therefore the unmoved mover, the uncaused cause, the first cause in every change. Every as in every.
I do not mean this slight review as the full proof. The details, again, are in Chapter 13.
Here is what is interesting. There is a causal chain, a here-and-now change which is actual and which turns a potential into an actuality, i.e. makes a change. There is the first or primary cause, which is God, followed by the series of secondary causes.
Could these secondary causes include acts by angels (good or bad)? Certainly.
God is immaterial, the scroll bar and your hands and arm are material. So are the muscles, chemical, electrons, and some other things below that. But as we get lower, we get further from materiality. Quantum materials exist as both actuality and potentiality. Strings, they say, are only two-dimensional curls of strange matter. What’s below strings? Something one dimensional? Why not? And what’s below that? The non-material. Given that God is at base, and God is immaterial, yet the material moves, there must be some way for the two to interact.
God could set the chain in motion, to make a pun, and assign the real labor of secondary causes in the immaterial to angelic beings. Every time? I have no idea.
Consider angels have to make a living, too. So it could very well be that certain non-material beings are assigned specific duties, duties regarding types of act or in definite places. There is holy water, relics, other blessed items. Meaning, perhaps, the assignment of particular non-material individuals to the secondary causes associated with these items. We also have the idea of guardian angels, which are beings that follow each of us about and, at times, interact with us, at least with our non-material intellects.
This idea is no different. And accords with ideas and notion every culture save our own, deep as it is into scientism, has had.
We, even the atheists among us, tend to view angels as bewinged beings that show up with soft glows behind them, speak in thee and thous, use cushy vowels, and dispense greeting card wisdom. Demons are rare but inveterately evil, ugly with snotty gleaming features, their whole being bent on corrupting or damning us.
This is a rather boring story, unlikely to be true. Instead, like us, non-material beings have personalities. Everyone but us has always thought so, though we do not call these beings “gods” as they did. Why should each and every demon care in just the same way about your demise? Could not some instead be incorrigible, pranksters, imbued with twisted senses of humor? Could some angels be a trifle bored with being just on this side of tears? Could not some, albeit in complete accord with God’s will and acting well within orders, carry out their task with more or less assiduity or with regard to your feelings?
We don’t see, often, what we don’t look for.