The following is an excerpt from Practical Religion by J.C. Ryle.
Let us settle it firmly in our minds — that the Lord’s Supper was not given to be a means either of justification or of conversion. It was never meant to give grace — where there is no grace already; or to provide pardon — when pardon is not already enjoyed. It cannot possibly provide what is lacking, with the absence of repentance to God, and faith toward the Lord Jesus Christ. It is an ordinance for the penitent, not for the impenitent; for the believing, not for the unbelieving; for the converted, not for the unconverted. . . . The simplest statement of the benefit which a truehearted communicant may expect to receive from the Lord’s Supper, is the strengthening and refreshing of our souls — clearer views of Christ and His atonement, clearer views of all the offices which Christ fills, as our Mediator and Advocate, clearer views of the complete redemption Christ has obtained for us by His substituted death on the cross, clearer views of our full and perfect acceptance in Christ before God, fresh reasons for deep repentance for sin, fresh reasons for lively faith — these are among the leading returns which a believer may confidently expect to get from his attendance at the Lord’s Table. He who eats the bread and drinks the wine in a right spirit — will find himself drawn into closer communion with Christ, and will feel to know Him more, and understand Him better.
No, Christ died once for all. The Lord’s Supper is a covenant meal celebrating Christ’s atoning work; as it is also a means of strengthening our faith as we look to him, and a foretaste of the future feast. But those who take part with unrepentant hearts eat and drink judgment on themselves.