There is a Star Trek Voyager episode where there is an alien race conducting medical tests on the crew, but the people cannot see them. No one knows that they are there, but they do have headaches and medical issues. But then the doctor (He is a special doctor that really is not real but a hologram. He is a “Holadoc”) thinks of changing one of the character’s vision (For non Star Trek people, 7 of 9 is a special character who had been abducted and altered by a race called the Borg. Anyways, what you need to know is she can have her vision altered). Then 7 of 9 can see these aliens doing this. Here is the connection to our Christian life: we also have spiritual warfare going on but we cannot see it. (Eph 6:12) They could not see these aliens doing this and we also cannot see the Spiritual Warfare going on, but it is going on.