While Satan may appear frightening, he has already been conquered by Jesus Christ.
Satan and his demonic allies can appear frightening to us, scaring us in a variety of ways.
However, St. John Paul II believed that Christians should not fear Satan, provided that we fully embrace the victory of Jesus Christ.
In a general audience in 1999, he explained why the fear of Satan should be absent from our live
We believe that Jesus conquered Satan once and for all, thereby removing our fear of him. To every generation the Church represents, as the Apostle Peter did in his discourse to Cornelius, the liberating image of Jesus of Nazareth who “went about doing good and healing all that were oppressed by the devil, for God was with him” (Acts 10:38).
The true key for us in removing our fear of Satan is fully accepting that victory of Jesus Christ in our lives.
If, in Jesus, the devil was defeated, the Lord’s victory must still be freely accepted by each of us, until evil is completely eliminated. The struggle against evil therefore requires determination and constant vigilance. Ultimate deliverance from it can only be seen in an eschatological perspective (cf. Rv 21:4).
Often we are afraid of Satan and his demonic forces when we begin to doubt Jesus’ power. We think that Satan is more powerful, when in truth, he runs away like a coward when the name of Jesus is uttered.
If we have a firm and confident faith in Jesus Christ, we should have nothing to fear.