There’s a guy on the internet who claims to believe a large chunk of the Bible but – oh dear – has come to the conclusion that Jesus is not God. He’s even self-published a book about it.
He goes to biblical studies conferences and wrote of his experience talking to a prominent American New Testament scholar. He seemed surprised when the scholar responded: “You’ll never convince me”. The denier of the Trinity said: “He had no interest in seeing my book”.
Chapter five of 1 John takes on this sort of theological weirdness, in verses 6 to 10. The disciple of Jesus is responding to a specific heresy that had arisen.
Cerinthus had been claiming that Jesus was not God but had merely been an ordinary man who had been occupied by the spirit of the Christ when he was baptised. The spirit had entered the body as a dove. This spirit performed all the miracles, but had left Jesus’s body prior to the crucifixion. The heresy also involved two gods, the lesser god who had created the Earth and set up Judaism, and now a higher deity who Jesus taught about.
So John rejects the error by saying (CSB):
Everyone who believes that Jesus is the Christ has been born of God, and everyone who loves the Father also loves the one born of him…
Who is the one who conquers the world but the one who believes that Jesus is the Son of God? Jesus Christ—he is the one who came by water and blood, not by water only, but by water and by blood. And the Spirit is the one who testifies, because the Spirit is the truth. For there are three that testify: the Spirit, the water, and the blood—and these three are in agreement.
So Jesus is the Christ, the Messiah. His attribute as the Messiah wasn’t temporary: it’s not merely related to his baptism in water by John the Baptist. He was still the son of God when the gospel of John says “one of the soldiers pierced Jesus’ side with a spear, bringing a sudden flow of blood and water”.
People can make all the claims they like, but how do we discern what is true? John says that three things are “in agreement” – the water, the blood and the Spirit. F.F. Bruce explains in The Epistles of John:
It is in the community who hold fast to what they were taught from the beginning, those who believe in Him who came by water and blood, that the Spirit is present to “bear witness”; those who deny the truth conveyed by “the water and the blood” cannot lay claim to the Spirit who bears witness by means of these. The Spirit’s ministry in the world includes as one of its principal elements the bearing of witness to Christ…
The Spirit witnesses in the believer’s heart and in the believing community, and their experience of His power and guidance confirms the truth of the gospel to which they have committed themselves.
God wants Christianity to spread and for accurate information to be shared. Rather than just let his disciples rely on their first-hand witness statements of what God did through the cross, he opted to give them the Holy Spirit. As Jesus said in Acts 1: “you will receive power when the Holy Spirit has come on you, and you will be my witnesses in Jerusalem, in all Judea and Samaria, and to the ends of the earth.”