1 John 5:10 New American Standard Bible
10 The one who believes in the Son of God has the testimony in himself; the one who does not believe God has made Him a liar, because he has not believed in the testimony that God has given concerning His Son.
John doesn’t mince words. Those who reject Jesus as the Son of God and the truth of scripture have made God a liar. They have rejected the clear truth that God has displayed concerning His Son. Throughout Jesus earthly ministry in so many ways the Father testified to the Son and who He truly is. Jesus was only able to do what He did on the earth because the Spirit of God enabled Him. The authority Jesus has, has been given to Him by the Father.
Those who have come to faith in Jesus Christ have the inner witness of the Holy Spirit. Romans 8:16 tells us The Spirit himself testifies with our spirit that we are God’s children. It is the Spirit of God who leads and guides us into all truth. It is the Spirit of God who opens our eyes to see and enables our hearts and minds to understand that Jesus is the Son of God.
When a person comes to the point of salvation it is the Spirit of God who convicts and brings that person to a place of repentance. Their eyes are opened to the reality they are a sinner in need of a savior. When that person places their faith and trust in Jesus Christ, it is in that moment the Spirit of God comes to live inside them and as they walk with the Lord each day, spending time in God’s word and in prayer, it is the Spirit of God who opens their understanding to truth.
Those who reject Jesus Christ and who He is are without hope. They make God a liar. It is clear from scripture that Jesus is declared to be the Son of God and God Himself. This is the distinction of Christianity. Some claim Jesus was mere a kind teacher or a prophet. Some will claim that others are on the same level with Jesus such as those who pray to Mary or angles. But it is Christ alone on which all things are built. It is upon Christ alone that we build our lives and our faith. But having a right understanding of who Jesus is, is essential for living out the Christian life in victory.