I am ever more convinced that evil requires our consent to harm us - and that most of the strategizing of evil is directed at getting people to consent to evil - to invite evil into the soul.
And fear is the main (but not only) way that people are induced to invite evil - because fear is a kind of sin, and needs to be discerned and repented in order to lose its malign effect
Of course, this is a mortal life in an entropic world; and we must accept that death and decay are necessary parts of our experience. For example; you and I are still alive because we have something important to learn from this world; and nobody can reach eternal Heavenly life except via death.
So, contrary to the teachings of This World; we must learn not to fear the basic nature of this life - and to regard this life as essentially good if we (as individuals) take the opportunities it offers us.
At the same time, Christians must recognize the transitional nature of this world. This mortal life is vital - but secondary to eternal resurrected life.
The combination means that Christians cannot legitimately deal with fear by ignoring the world - for Christians this amounts to pretending that evil does not exist, and pretending there is no spiritual war: pretending that evil is not-really attacking us...
Christians need both to recognize and to reject evil.
We don't need to 'think about' evil beyond this recognition and rejection, we don't need to understand all about it - but we do need to know evil when it impinges directly upon us - which it will, later if not sooner.
At present the world is ruled by evil, and consequently our lives are full of threats designed to evoke the sin of fear. Most of these threats are unreal; because evil is a liar - systematically and compulsively.
(Even when evil makes a true statement, speaks a true fact (something which is very painful for an evil being) this 'fact' will always be presented in a false and misleading framework. Specific truth will be put to the service of general falsehood; bits of reality will be twisted to reinforce the unreal.)
Nonetheless, among the mass of lies to induce fear, there will also be scattered and seeded real threats - threats to our health, happiness, lifespan...
Yet these 'true threats' must be treated with the same contempt as the mass of fake threats: which is to say, we must never allow ourselves to become colonized by fear, from whatever cause or no cause; and must always recognize and reject fear when it arises in us - and whether the threat is fake or indeed real.
When we feel fear arise in us, we need to recognize it as a doorway to evil being opened by purposive evil; a door which we our-selves are opening, and which we ourselves need to shut as fast as possible - before evil can pries it wider, enter in force, and begin colonizing our soul.
How can a Christian close that door of fear? By faith and hope; faith in God who is the creator of this world, and who loves us each as his child - and hope in eternal resurrected life by following Jesus through death to Heaven.
Faith and hope are what enable us to learn from this life and its experiences - instead of the false alternatives of being overwhelmed by threats or ignoring them.
So, when we feel that stab of fear which the evil overlords work so hard to induce in us; then we can recognize the fear as a sin, place it in the eternal and joyous context provided by the faith and hope - and regard fear as just another chance to learn necessary lessons from our mortal life, living in this world.