The Cup of the Covenant

When Jesus instituted the Lord's Supper, he told the disciples that the cup was the start of a new covenant. When covenants were formed in the Bible, two or more parties would commit to one another, offer a sacrifice to make that commitment official, and then celebrate this new relationship with a shared meal. Viewed in this light, Communion is a weekly opportunity to "renew our vows" with God, and it's an ongoing reminder of God's commitment to his side of the Covenant.