According to the evidence of the Bible, it is the Holy Spirit, water, and blood that testify. So these three are one. Who, then, does this testify? The Holy Spirit, water, and blood testify of the Savior Yehoshua. 

[1 John 5:7~9] For there are three that testify: the Spirit, the water and the blood; and the three are in agreement. 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. 

Thus the Son of God reveals himself as the Savior by the Spirit, by water, and by blood. Yehoshua, who appeared as the Son of God, testified through this that He was the Savior. 

[1 John 5:6~7] 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: 

Yehoshua testified with water and blood that He was the Savior. Here, water refers to the words of the water of life that springs out of the boat, and the blood testifies that He will be sacrificed on the cross. Yehoshua preached the word of God for three years. And by the sacrifice of the cross he proved himself to be the Savior by water (the Word of God) and blood (the sacrifice of the cross). Therefore, John could testify that Yehoshua came by water and blood. 

[John 19:33~35] But when they came to Jesus, they saw that he was already dead, and they did not break his legs. One of the soldiers stuck his spear into Jesus' side, and blood and water came out. We know this is true, because it was told by someone who saw it happen. Now you can have faith too. 

Yehoshua shed blood and died on the cross after preaching the word of God for three years. And he came to the saints as the Holy Spirit after the resurrection and ascension. When John saw this, he testified that he came with water, blood, and the Holy Spirit. Therefore, the Son of God must come with water, blood, and the Holy Spirit, which is a sign of the Bible that he is the Son of God. The Bible prophesied of water, blood, and the Holy Spirit. Let's look at the water prophecy first. 

[Ezekiel 36:24~25] I will gather you from the foreign nations and bring you home. I will sprinkle you with clean water, and you will be clean and acceptable to me. I will wash away everything that makes you unclean, and I will remove your disgusting idols. 

God prophesied that the people of Israel would be washed from defilement by sprinkling them with clean water before they were led from the Babylonian captivity to their homeland. But this is not real water, but a metaphor for the Word of God. The history of physical Israel in the Old Testament is a prophecy that will be fulfilled for spiritual Israel. Therefore, the Son of God must wash away the sins and defilements of the saints with the crystal-clear Word of God before entering the kingdom of God. 

[Zechariah 13:1 ] "On that day a fountain will be opened to the house of David and the inhabitants of Jerusalem, to cleanse them from sin and impurity. 

And the Son of God will shed the blood of suffering for the sins of the people. In this regard, the Bible records: 

[Isaiah 53:4~6] Surely he took up our infirmities and carried our sorrows, yet we considered him stricken by God, smitten by him, and afflicted. But he was pierced for our transgressions, he was crushed for our iniquities; the punishment that brought us peace was upon him, and by his wounds we are healed. We all, like sheep, have gone astray, each of us has turned to his own way; and the LORD has laid on him the iniquity of us all. 

Thus the Son of God is shed blood. But he prophesied that he would come again in the body of a saint through the Holy Spirit. The Bible prophesied about this. 

[Isaiah 59:20~21] "The Redeemer will come to Zion, to those in Jacob who repent of their sins," declares the LORD. "As for me, this is my covenant with them," says the LORD. "My Spirit, who is on you, and my words that I have put in your mouth will not depart from your mouth, or from the mouths of your children, or from the mouths of their descendants from this time on and forever," says the LORD 

As such, Yehoshua, who came as the Son of God, preached the word, suffered and died. But he came again in the body of a saint by his Holy Spirit. So the Bible prophesied that the Son of God would come with water, blood, and the Holy Spirit. Therefore, Yehoshua, who came as water, blood and the Holy Spirit, is the Son of God. And it proves that only he has life. 

[1 John 5:11~12] And this is the testimony: God has given us eternal life, and this life is in his Son. He who has the Son has life; he who does not have the Son of God does not have life. 

Those who receive the Holy Spirit of Yehoshua have received the Son of God. And he receives eternal life. The coming of water, blood, and the Holy Spirit is a sign that only the Son of God can do. Without the Holy Spirit, we cannot walk in the way of water, blood, and the Holy Spirit. So these three are one. 

The two witnesses who appeared as the Son of God will go the way of Yehoshua. So they will prove that they are sons of God. 

[Revelation 11:10~12] The inhabitants of the earth will gloat over them and will celebrate by sending each other gifts, because these two prophets had tormented those who live on the earth. But after the three and a half days a breath of life from God entered them, and they stood on their feet, and terror struck those who saw them. Then they heard a loud voice from heaven saying to them, "Come up here." And they went up to heaven in a cloud, while their enemies looked on.