“You are already clean because of the word which I have spoken to you.”
John Calvin comments: “He is undoubtedly speaking about external preaching, because he specifically mentions ‘the word I have spoken to you.’ Not that words spoken by humans have such a great effect, but when Christ works in the heart by the Spirit, ‘the word’ itself is the instrument of cleaning.” (John: Calvin, The Crossway Classic Commentaries, p.354, emphasis mine)
But the Gospel is not merely “words spoken by humans.” Calvinists merely play lip-service to the supernatural power of the Gospel. According to Calvinism, man is so totally depraved that the Gospel has no effect upon him, and therefore, only a preemptive New Birth, rather than the Gospel, is what supplies faith and empowers man to receive God. In summary, Calvinism represents a significant demotion of the dynamite power of the Gospel.
Romans 10:17: “So faith comes from hearing, and hearing by the word of Christ.”