Everyone who believes that Jesus is the Christ is born of God, and everyone who loves the father loves his child as well. This is how we know that we love the children of God: by loving God and carrying out his commands. In fact, this is love for God: to keep his commands. And his commands are not burdensome, for everyone born of God overcomes the world. This is the victory that has overcome the world, even our faith. Who is it that overcomes the world? Only the one who believes that Jesus is the Son of God.
This is the one who came by water and blood—Jesus Christ. He did not come by water only, but by water and blood. And it is the Spirit who testifies, because the Spirit is the truth. For there are three that testify: the Spirit, the water and the blood; and the three are in agreement. We accept human testimony, but God’s testimony is greater because it is the testimony of God, which he has given about his Son. Whoever believes in the Son of God accepts this testimony. Whoever does not believe God has made him out to be a liar, because they have not believed the testimony God has given about his Son. And this is the testimony: God has given us eternal life, and this life is in his Son. Whoever has the Son has life; whoever does not have the Son of God does not have life.
1 John 5:1-12 (NIV)