How do we know the efficacy of the Lord's Supper is true?

The Scriptures clarify that the Lord's Supper, while being a significant ordinance, does not convey grace by its mere observance. For instance, Judas Iscariot partook of the table without receiving any saving grace. The effectiveness of the Supper lies in its symbolism of faith in Christ's sacrifice rather than the act itself establishing grace. Therefore, we recognize that this ordinance is meant to strengthen believers' faith, reminding them of Christ's atoning work done on their behalf.