Jesus Christ is the One who came. Jesus came with water F19 and with blood. F20 Jesus did not come by water only. No, Jesus came by both water and blood. And the Spirit F21 tells us that this is true. The Spirit is the truth.
We believe people when they say something is true. But what God says is more important. And this is what God told us: He told us the truth about his own Son.
The person who believes in the Son of God has the truth that God told us. The person who does not believe God makes God a liar. Why? Because that person does not believe what God told us about his Son.