1 John 5:4 For whatsoever is born of God overcometh the world: and this is the victory that overcometh the world, even our faith.
5 Who is he that overcometh the world, but he that believeth that Jesus is the Son of God?

These two verses focus the emphasis on us defeating the deception of the devil. First we says we defeat Satan by being born of God and then that we overcome the world by our faith. Then again he emphasizes that we are overcomers because we have put our faith in the fact that Jesus is the Son of God. The victory over this world is when the world becomes unimportant in our life, and we are living to the day when we can go home to heaven and be with Jesus. Jesus defeated Satan on the cross. He defeated sin, as well. If we have received Jesus, then Jesus in us has overcome the world and Satan. We am living in the victory of Jesus.