Paul writes to the Corinthians that:
. . . Christ, our Passover lamb, has been sacrificed. Let us therefore celebrate the festival . . . (1 Corinthians 5:7-8 ESV)
Calvin comments on this, writing that:
Paul, having it in view to exhort the Corinthians to holiness, shows that what was of old figuratively represented in the passover, ought to be at this day accomplished in us, and explains the correspondence which exists between the figure and the reality. In the first place, as the passover consisted of two part—a sacrifice and a sacred feast—he makes mention of both. For although some do not reckon the paschal lamb to have been a sacrifice, yet reason shows that it was properly a sacrifice, for in that rite the people were reconciled to God by the sprinkling of blood. Now there is no reconciliation without a sacrifice; and, besides, the Apostle now expressly confirms if, for he makes use of the word θύεσθαι, which is applicable to sacrifices, and in other respects, too, the context would not correspond. The lamb, then, was sacrificed yearly; then followed a feast, the celebration of which lasted for seven successive days. Christ, says Paul, is our Passover. He was sacrificed once, and on this condition, that the efficacy of that one oblation should be everlasting. What remains now is, that we eat, not once a year, but continually.
Thus, weekly communion: we, who have a perpetual sacrifice and are made permanently holy, are continually in a festal season.