John Calvin Commentary 1 Corinthians 5:8

"wherefore let us keep the feast, not with old leaven, neither with the leaven of malice and wickedness, but with the unleavened bread of sincerity and truth." — 1 Corinthians 5:8 (ASV)

Now, in the solemnity of this sacred feast, we must abstain from leaven, as God commanded the forefathers to abstain. But from what leaven? As the outward passover was to them a figure of the true passover, so its accompanying elements were figures of the reality which we today possess.

If, therefore, we wish to feed on Christ’s flesh and blood, let us bring to this feast sincerity and truth. Let these be our loaves of unleavened bread. Away with all malice and wickedness, for it is unlawful to mix leaven with the passover. In short, he declares that we will be members of Christ only when we have renounced malice and deceit.

In the meantime, we must carefully observe this passage, as showing that the ancient passover was not merely μνημόσυνον (a memorial of a past benefit) but also a sacrament, representing Christ who was to come, from whom we have this privilege, that we pass from death to life. Otherwise, it would not be true that in Christ is the body of the legal shadows (Colossians 2:17).

This passage will also serve to set aside the sacrilege of the Papal mass. For Paul does not teach that Christ is offered daily, but that the sacrifice having been offered up once for all, it remains for the spiritual feast to be celebrated throughout our whole lives.