5:5. Who is he that overcometh the world, but he that believeth that Jesus is the Son of God?
5:6. This is he that came by water and blood, Jesus Christ: not by water only but by water and blood. And it is the Spirit which testifieth that Christ is the truth.
Came by water and blood. . .Not only to wash away our sins by the water of baptism, but by his own blood.
5:7. And there are Three who give testimony in heaven, the Father, the Word, and the Holy Ghost. And these three are one.
5:8. And there are three that give testimony on earth: the spirit and the water and the blood. And these three are one.
The spirit, and the water, and the blood. . .As the Father, the Word, and the Holy Ghost, all bear witness to Christ's divinity; so the spirit, which he yielded up, crying out with a loud voice upon the cross; and the water and blood that issued from his side, bear witness to his humanity, and are one; that is, all agree in one testimony.
5:9. If we receive the testimony of men, the testimony of God is greater. For this is the testimony of God, which is greater, because he hath testified of his Son.
5:10. He that believeth in the Son of God hath the testimony of God in himself. He that believeth not the Son maketh him a liar: because he believeth not in the testimony which God hath testified of his Son.
He that believeth not the Son, etc. . .By refusing to believe the testimonies given by the three divine persons, that Jesus was the Messias, and the true Son of God, by whom eternal life is obtained and promised to all that comply with his doctrine. In him we have also this lively confidence, that we shall obtain whatever we ask, according to his will, when we ask what is for our good, with perseverance, and in the manner we ought. And this we know, and have experience of, by having obtained the petitions that we have made.
5:11. And this is the testimony that God hath given to us eternal life. And this life is in his Son.