Philosophers have often talked about the difference between the world as it really is, and the world as we humans perceive it.
What does that mean?
Wherever you are right now, make your room as silent as you can. No music, no radio, no TV, no talking. Just, to the degree possible, pure silence.
The only problem? If you were to turn on the radio, or open a radio app on your smart phone, guess what? Of course, the room would fill with sounds, music, with whatever the app opened to.
Where did all that sound come from? Where did it originate from? Not from the radio, not from the smart phone. Of course not. It originated in the air all around you, as radio waves. However, given the way that you are constructed, given the way that your eyes and ears pick only certain frequencies, a whole other element of reality, as real as your own voice, exists all around you even though you are, in and of yourself, not able to pick it up.
In fact, chances are (depending on where you are at the moment) most of the world’s cell phone calls and text messages are in the very room with you right at this moment—a reality all around you that you are just not personally outfitted and wired to perceive.
Hence, if there ever was a generation of humans who, in principle, should believe in the existence of spiritual entities, it should be ours. The Bible talks about a spiritual warfare between good and evil powers that exist in the cosmos and that are active here: “For we do not wrestle against flesh and blood, but against principalities, against powers, against the rulers of the darkness of this age, against spiritual hosts of wickedness in the heavenly places” (Ephesians 6:12). Sure, we can't see them, hear them, feel, smell or taste them any more than we can the millions of cell phone conversations around us as well.
But we can know these powers are real, and are here, and that we can, by faith, claim Christ’s victory for us in this cosmic battle as well. For, as the Word said about Jesus, “Having disarmed principalities and powers, He made a public spectacle of them, triumphing over them in it” (Colossians 2:15). And His victory is ours as well, if we claim it for ourselves.