What does 1 Corinthians 11:28 mean?The Lord's Supper, also called communion, is a symbolic remembrance of the crucifixion of Jesus Christ (1 Corinthians 11:23–26). Jesus instituted this as a time of reflection and unity among His followers (Matthew 26:26–28). Some, like the believers in Corinth, miss those lessons entirely (1 Corinthians 11:17–22).
Paul has just written that to take part in the Lord's Supper in an unworthy manner makes a person guilty of the body and blood of Christ (1 Corinthians 11:27). The observance of communion is sacred, with sacred implications. The problem is not in performing the wrong steps or failing to meet some legalistic standard. There is wide freedom in exactly how communion can be observed. What Paul condemns here is to participate without a solemn appreciation for what the sacrament represents. Those who act carelessly risk earning an elevated share in the responsibility for Christ's death on the cross.
As such, each person should examine themselves before eating the bread that represents Christ's body and drinking the cup that represents His blood. Then, when confident that they are not doing so in an unworthy way, those present should eat and drink. But not before then.
Obviously, this leads to the question of what, specifically, Christians should search for in themselves before taking part in communion. The most commonly-understood practice is for participants to take a moment to confess to God any un-repented sin and receive His forgiveness in Christ. The taking of the bread and wine is meant to involve "remembrance" of Jesus' sacrifice (Luke 22:19). Believers should humbly acknowledge the gift of grace given to them through Jesus' shed blood and broken body before observing the Lord's Supper. Those who know—or should know—they are blatantly in contrast to that mindset should not partake.
It's likely Paul had specific sins in mind. In this context, that probably included a lack of love and concern on the part of wealthy believers for the poorer Christians among them.