Victory over the world (and by the world I mean those who do not not know the truth – those who are false prophets and who are at the whim of any spirit and ultimately are separated from God) comes from believing that Jesus has the power to redeem our souls. And when we have faith in this, the testimony of God – His truth and love – will live in us.
By His love there is no fear.
So Faith is the antidote for fear.
1st John 4:1-3 Beloved do not believe every spirit but test the spirits to see whether they are from God, because many false prophets have gone out into the world. By this you know the Spirit of God: every spirit that confesses that Jesus Christ has come in the flesh is from God and every spirit that does not confess Jesus is not from God. . .
1st John 4:16-18 We have come to know and have believed the love which God has for us. God is love, and the one who abides in love abides in God, and God abides in him. By this, love is perfected with us, so that we may have confidence in the day of judgement; because as He is, so also are we in this world. There is no fear in love; but perfect love casts out fear, because fear involves punishment, and the one who fears is not perfected in love.
1st John 5: 4-5 For whatever is born of God overcomes the world; and this is the victory that has overcome the world – our faith. Who is the one who overcomes the world, but he who believes that Jesus is the Son of God?