“It is the Spirit who gives life; the flesh profits nothing; the words that I have spoken to you are spirit and are life.”
John Calvin comments: “We also note that Christ links ‘life’ with the Spirit. He calls his Word ‘life’ because of its effect, as if he had called it life-giving. But he says that it will only be life-giving to people who receive it spiritually; others will derive death from it. For the godly, this is a most delightful commendation of the Gospel, because they are assured that it is appointed for their eternal salvation. Yet at the same time they are reminded to work hard to show that they are genuine disciples.” (John: Calvin, The Crossway Classic Commentaries, p.175, emphasis mine)
Here are some of those “words” that Jesus spoke:
John 3:16: “For God so loved the world, that He gave His only begotten Son, that whoever believes in Him shall not perish, but have eternal life.”
John 4:13-14: “Jesus answered and said to her, ‘Everyone who drinks of this water will thirst again; but whoever drinks of the water that I will give him shall never thirst; but the water that I will give him will become in him a well of water springing up to eternal life.’”
John 5:24: “Truly, truly, I say to you, he who hears My word, and believes Him who sent Me, has eternal life, and does not come into judgment, but has passed out of death into life.”
John 6:63: “It is the Spirit who gives life; the flesh profits nothing; the words that I have spoken to you are spirit and are life.”
Through Jesus’ words, the lost receive life. However, how would John 6:63 make sense in Calvinism? Those who are allegedly, preemptively made in Christ, already have passed out of death and into life. For them, what else can the Gospel accomplish? This verse only makes sense for those who need life, rather than for those who already secretly have it.