VERSE 5 ends with the words 'Who is it that overcomes the world? Only he who believes that Jesus is the Son of God'. In these next verses 6-11 John is at pains to make clear the truth about Jesus as the one who enables us to overcome the world. Great strength is needed in order to obtain victory over the world, which John tells us is under the authority and power of the evil one (1 john 5: 19), and so only the power of the Son of God, and his victory over Satan can bring about this victory.
So John reminds us of the tremendous victory of Jesus over Satan and the world. He tells us he is the one who came by water and blood, even Jesus Christ. He goes on to inform us that Jesus did not come just by water, but also by blood, and that together with these two factors is the Holy Spirit who testifies to us that Jesus is the victorious Saviour. So how do we understand Jesus coming by water and blood?
Here is a rather enigmatic statement which is puzzling. We have water and blood joined together in John 19: 34 where we are told that when the soldier pierced the side of the dead Jesus on the cross, both water and blood flowed out of the wound. However this does not entirely help us except to focus our understanding that it was in his death on the cross that the victory of Jesus over the world, and its prince Satan, is found. This is in the active atonement for sin that Jesus accomplished by his death, where he took all the power of Satan to hold the true disciple of Jesus under the sentence of death, the punishment for sin, that is having taken our punishment for sin, Satan's hold on us is removed. Jesus won this victory over death by suffering the whole punishment of God against sin in the place of all who believe on him as their Saviour.
From this we are able to see that when John speaks of Jesus coming with blood he is referring to the cross as the centre of Christ's victory. The reference to water is less clear. Water cleanses from dirt and defilement, but this is external, and it is only the blood of Jesus that cleanses the heart and the soul within. This emphasis shows that outward righteous in moral living can never save from the wrath of God, because defilement in the heart still remains. So we may receive the washing of baptised, but this does not cleanse the heart. Baptism symbolises washing of regeneration but does not accomplish new birth which is only granted by Jesus through faith in him as Saviour through the cross.
In verse 7 John tells us that we have a threefold testimony to life and victory in Christ, but it is only through the operation and the gift of the Holy Spirit to dwell with in us that grants us such appreciation of the saving meaning of Christ's death, that we have no doubt that we have victory of sin, Satan and the world, as we cast our whole trust upon Jesus and the righteousness he has worked for all true believers, and is imputed to them for eternal salvation.
John goes on to seal up this assurance by saying in verse 9 'we accept man's testimony, but God's testimony is greater because it is the testimony of God, which he has given about his Son'. God cannot lie. What he affirms is the truth. God affirmed that Jesus was his only begotten Son, in whom he was well pleased at the baptism of Jesus by John the Baptist, and again to the three disciples who accompanied Jesus when he was transfigured on the mountain.
Then in verse 10 John declares that all who have received, by faith, Jesus as their sin-bearer and Saviour have this testimony concerning Jesus sealed in their hearts by the Holy Spirit.
Then comes, in the rest of verse 10, the condemnation, declared by John concerning those who do not truly believe the truth God declares concerning his Son. He declares the evil of unbelief. He declares that such people call God a liar because they do not believe the testimony God has given concerning his Son.
This applies to all those within the church, who exalting their own finite reason, 'still in darkness of unbelief', over the word of God in the Bible, reject the testimony of Scripture, the infallible word of God, to Christ. Here we have the lie Satan has implanted in the church today that the Bible simply contains the word of God, and the truth much be searched out by human wisdom. By this means teachers in the visible church can deny the truth testified by God to his Son.
John finishes with a concise declaration of the testimony God has given concerning his Son. This is in the words of verses 11 and 12. God has given eternal life. Eternal life cannot be earned or merited by human effort, for no human effort is perfect as God demands perfection. Eternal life can only be received as a gift, which God, in Christ, in grace has provided for all who receive his testimony concerning his Son.
This is affirmed in the next sentence where John declares eternal life is only found and provided in Jesus who has won it for those who receive it by faith.
John goes on to declare that eternal life is only found in Jesus, God's Son, when there is belief in the testimony of God concerning his Son. This is the only way we have the Son of God. John seals his argument with the warning that if there is no true receiving of Jesus, and where the testimony of God concerning his Son is diminished or denied, then there is no eternal life.