What does it mean to conquer the world? Does it mean that you control all the land? Does it mean that people obey you? St. John does not think so. He says that the the victor over the world is the one who believes that Jesus Christ is the Son of God. Alexander the Great spent his entire life leading an army on the march. He died at 32 having conquered the world, or so people said. How could he have conquered the world when every day of his life was defined by the world? It seems, rather, that the world conquered him.
The battle between us and the world does not take place in Europe or Asia or Africa. It takes place in our souls. Conquering the world does not mean controlling billions of people. It means controlling ourself, and this begins with believing in the Savior of the world, Jesus Christ. It is by submitting ourselves to the true king of heaven and earth that we can rule under him.
The necessary faith is not blind faith. It comes through the testimony of God. We know the testimony of the Holy Spirit, who descended on Jesus at his baptism like a dove. Then there is the testimony of the water. Water obeyed Jesus Christ. He could walk on water. He changed water into wine. He calmed the sea with a word. Who can do that except God?
Then there is the testimony of the blood. Perhaps Jesus was just a magician or an alien from another planet with advanced technology. No, because the testimony of the blood is the final testimony: he died for us. He suffered and died for us. It is this combination of power and weakness that equals infallible testimony. If Jesus were weak, why was he so powerful? If he was powerful, why did he die for us? He must be someone of great power who also loved us. Who else could that be except God?