This, Jesus the Son of God, came by water and blood. The reference is most likely the virgin birth. While both blood and water are involved, it seems, as the next couple lines indicate, the water represents the Spirit, and the blood are the human element—the Son. The water in scripture is symbolic of life, cleansing, and tin the Gospels can reference the Spirit. As John’s next line states, the coming was not “water alone. But rather water and blood. Life and that which carries life. It is more understood that it is the Spirit who is involved with both water and blood—as it testifies to both— the truth and its involvement. The Spirit, the water, and the blood agreeing should be a place of literalism here. the elements themselves cannot speak, but they can represent the message spoken. The blood is that which contains life of the create, it points to its creator. The water is a part of the ordered chaos in Genesis—representing the vitality of life itself. Lastly, without the source of breath (ruach) neither of blood nor water breathes—the source is the Sirit. God, the Creator, the Spirit, the Son has come.
In John’s Gospel, 5:25-40, Jesus gives the religious leaders and Israelites his testimony. He is the life of the Father. It is the purpose of which He came—He did in accordance with the Father—to bring life to the world. He testifies that Father, who Himself testifies about Jesus in the scriptures. The life of God is not in the scriptures—but it points to whom life is found, and Jesus states, I am He. The testimony of man, John mentions here is in regards to those like John Baptist, who point to the Son. yet, the testimony of the Son is great as he in flesh is the life of the Father to the world. Those who trust in the life offer by Jesus are kept in Him. To deny the word or testimony is to call out the Father and the Son. Then John repeats the testimony. The Son of the Father came to give life unto the age to come. He wo does not trust in this will not get the life in the age to come.
"He who has the Son has life; he who does not have the Son of God does not have life” 1 John 4:12
To have is akin to “to hold”. As we eloquently say in marriage vows, “to have and to hold.” Those who “have” the Son of God “have” the gift thereof. The one who John described throughout his letter. He or she who trusts in the Son for life, cleanses of sin, and has forever forgiveness. The one who “has” loves on—acts on love toward others. they demonstrate the fruit of the Spirit of joy, love and peace. The one who does NOT “have” will not trust in the Son for life and does not have others as he ought. John writes these for his listeners confidence. Life in the age to come, kingdom of Jesus, is present and forth coming. It is seen in the sacrificial acts of love in His followers.