1 John 5:10 says, “He who believes in the Son of God has the witness in himself; he who does not believe God has made Him a liar, because he has not believed the testimony that God has given of His Son.”
God the Father’s witness about His Son is that God sent His Son into this world to take all our sins onto Himself once for all through Jesus’ baptism, and that God completed our salvation by having Jesus die on the Cross shedding His blood for our redemption. What is important on our part is whether we believe in this or not.
God the Holy Spirit has descended upon the hearts of us, the believers of God’s evidence, and has testified to our salvation more intensely.
The water, the blood, and the Holy Spirit are not only the evidence of God’s salvation for us but also the benchmark of the Truth.
Thus, if any of us does not believe in Jesus Christ our Savior as having come by the water, the blood, and the Holy Spirit, that person makes God a liar.