Fear is always real. It is the object of our fear that may be illusory.
Confusing the two is not so easy to get a handle on emotionally.
If I step out of my back door and think the water hose coiled by the steps are a snake I will get a jolt of adrenaline that is very real.
I will probably jump back with my heart pounding wildly in my chest. All very real.
But, the object of my fear is a water hose.
The Fear is real but the snake is illusory.
Fear of Demons is real fear. Demons are not.