How do we know the Lord's Supper is for believers?

The institution of the Lord's Supper was specifically given to the apostles and, by extension, to all believers, as a means to remember and proclaim the death of Christ until He returns. It is emphasized that the elements of the Supper represent His body and blood, given for the believers. According to Ephesians 2:8-9, salvation is described as a gift of grace through faith, reiterating that the Supper is a remembrance for those who have accepted that grace, making it a sacred act meant for believers who partake in faith.