John Calvin Commentary 1 Corinthians 15:20

"But now hath Christ been raised from the dead, the firstfruits of them that are asleep." — 1 Corinthians 15:20 (ASV)

But now hath Christ risen. Having shown what dreadful confusion regarding everything would follow if we were to deny that the dead rise again, he now again assumes as certain what he had sufficiently established previously — that Christ has risen; and he adds that he is the first-fruits, by an analogy taken, as it appears, from the ancient ritual of the law. For as in the first-fruits the produce of the entire year was consecrated, so the power of Christ’s resurrection is extended to all of us — unless you prefer to understand it more simply — that in him the first fruit of the resurrection was gathered. I prefer, however, to understand the statement in this sense — that the rest of the dead will follow him, as the entire harvest does the first-fruits; and this is confirmed by the succeeding statement.