We should take the Lord’s Table seriously because the Lord Himself does. He “fences” His Table, He protects it from abuse, not always at the table itself, but afterward, which does cause much effect. Paul wrote in 1 Corinthians 11:
Whoever, therefore, eats the bread or drinks the cup of the Lord in an unworthy manner will be guilty of profaning the body and blood of the Lord. … Anyone who eats and drinks without discerning the body eats and drinks judgment on himself. That is why many of you are weak and ill, and some have died. (1 Corinthians 11:27, 29–30, ESV)
Some sins, here a disrespect of communion, do lead to suffering, sickness, and “sleep” in a casket. “Let a person examine himself, then, and so eat of the bread and drink of the cup” (verse 28). Check the system before you take off so the wheels don’t fall off down the road.
But this exhortation by Paul is no scare tactic. It’s not meant to make us panic, to consume us with pre-trip checklists so that we never get out of the driveway. The exhortation protects us from failure to take our sin and His sacrifice seriously. When we do that, we can enjoy the meal.
His sacrifice was for sin, on behalf of sinners. The bread and the cup represent His body and blood given for sake of our forgiveness and our cleansing. By His wounds we are healed. We don’t heal ourselves before we come to this table. Only Christ can make anyone well and that’s why we exult in Him, not in our examination.