"(He's not talking about optional matters of doctrine,) Rather, he's speaking of things that are commanded. Nadab and Abihu (Leviticus 10) are great examples of how obeying God in the specifics matter. 1 Cor 11:29-30 is a NT example in a similar fashion. In that passage we're warned that we can't just eat and drink the Lord's supper any way we please. If we do, the Lord may kill us." - Something somebody recently told me about the consequences of disobeying God.
1 Corinthians 11: "28 Everyone ought to examine themselves before they eat of the bread and drink from the cup. 29 For those who eat and drink without discerning the body of Christ eat and drink judgment on themselves. 30 That is why many among you are weak and sick, and a number of you have fallen asleep. 31 But if we were more discerning with regard to ourselves, we would not come under such judgment."
If you are spiritually healthy, then you are physically healthy might be a simple way to sum up the ancient world's beliefs on health and wellness. For example, in John 9:2, "His disciples asked him, “Rabbi, who sinned, this man or his parents, that he was born blind?”"
Even today the story of Ananias and Sapphira is a dire warning of the consequences of spiritual sickness. So it's not surprising somebody today might read verse 30 and and assign blame to the church; improper communion = unhealthy believers. They might even take it as a warning for today ... they might go so far as to say, "If Christians were better at following what the Bible says, then they'd be slimmer, healthier, without disease, cancer-free, beautiful and prosperous in every way."
But lets explore that verse in detail: If the believers had perfect communion, would they have lived? Not necessarily, death is the natural conclusion of life. If the believers had perfect communion, would they have been neither sick nor weak? In the physical sense, nothing stops aging and weakness with time or sicknesses. Any number of activities weakens our immune system making people more susceptible to disease and sickness for a time. Resting allows our bodies to give it's full attention to fighting off sickness. if the prosperity gospel people are right, then weakness, sickness, and death was the result of the believers sin. In that case, Tabitha (Acts 9) must have been really naughty to have grown sick and then died. Peter only had to tell her to 'get up' to restore her to life. He didn't have to tell her to repent of her sins.
This is the description of their improper communion: "So then, when you come together, it is not the Lord’s Supper you eat, 21 for when you are eating, some of you go ahead with your own private suppers. As a result, one person remains hungry and another gets drunk. 22 Don’t you have homes to eat and drink in? Or do you despise the church of God by humiliating those who have nothing? What shall I say to you? Shall I praise you? Certainly not in this matter!"
Communion today really doesn't look like that, in most churches I've been to we all get a sip of juice (not wine) and a small oyster cracker (not bread.) It's not possible to eat your fill or get drunk even if you wanted to. What was improper was that the Christians were being exclusive gluttons with a first-come-first-serve attitude. There aren't any specific commands about the style, order, timing, etc. of proper communion - and no two churches I've been to ever have done it exactly alike. Some churches even recognize that people have allergies to wheat and serve a gluten-free alternative to communion crackers / bread. (Other churches would tell gluten-sensitive people and people with Celiac disease that if they prayed harder, they would not be allergic to wheat.)
The correction: "For I received from the Lord what I also passed on to you: The Lord Jesus, on the night he was betrayed, took bread, 24 and when he had given thanks, he broke it and said, “This is my body, which is for you; do this in remembrance of me.” 25 In the same way, after supper he took the cup, saying, “This cup is the new covenant in my blood; do this, whenever you drink it, in remembrance of me.” 26 For whenever you eat this bread and drink this cup, you proclaim the Lord’s death until he comes."
But isn't the real problem always the hear-attitude? "27 So then, whoever eats the bread or drinks the cup of the Lord in an unworthy manner will be guilty of sinning against the body and blood of the Lord. 28 Everyone ought to examine themselves before they eat of the bread and drink from the cup. 29 For those who eat and drink without discerning the body of Christ eat and drink judgment on themselves."
The difference between the Corinthian church and the D-I-Y Priests is they were both under different systems. The Priests were servants under The Law, with strict thou shalts and thou shalt nots, they were born to be the representation between God and man until a bridge could be established. They ultimately were not free to worship God in any other way that the one He had previously approved and instituted for the sole purpose for them to satisfy His holiness and righteousness. He was kind enough to let them know exactly how to do that. I would argue, however, that Jesus having died / resurrected had fulfilled the requirements of the law so that the 'one right way' was satisfied - making it possible to have many different and right ways to worship God - if it hadn't, then worship should only be based off of the Jewish Temple style - all other forms would have to be considered improper because they were not so thoroughly elaborated upon in the New Testament.
The Corinthian believers were from Greece, they had no Jewish background and had no practical experience with the God of the Jews - to them, their nation's (Rome's pantheon of) gods were superior conquerors over every other nations gods. Paul told the Athenians about this Unknown God, but how far that sermon had spread beyond the city is unknown. It really wasn't God that attracted them to Christianity, but Jesus - who would have been entirely different and distinct from the God of the Old Testament. Corinth was a city that sat on the peninsula at the narrowest point - they had command of two ports, sailors were frequent customers - and ruins of the city have revealed dozens of wine shops, the city, it seemed, never ran dry - there was always something strong to drink. What was improper about their communion wasn't that they didn't have the right kind of wine or bread, but some of them were having way too much and others weren't getting any at all. Paul's solution: If you're hungry, eat at home before-hand, make sure everybody gets to participate, and be more introspective about what the symbols of communion mean.
Jesus paid the price of The Law so that the Corinthians and other Gentiles could be grafted into the family of God. Jesus did not institute a replacement law system which orders communion to be exactly a like from one church to the next, being served at the pews by elders or deacons, having a small sip of grape juice in individual cups, and a small oyster cracker, reading the scripture, partaking of the elements at the same time, etc., there's not one right way to go about communion as long as your heart is ready and you are in the right state of mind. But our mass-consumption culture sort of treats it like an assembly line of worship - it doesn't always allow for individuals to do it differently than the rest or give people time to be introspective about what's going on in their hearts.
So when your Christianity boils down to your physical well-being being dependent on your spiritual well-being, it's time to really read what the scripture says: "“Neither this man nor his parents sinned,” said Jesus, “but this happened so that the works of God might be displayed in him. 4 As long as it is day, we must do the works of him who sent me. Night is coming, when no one can work. 5 While I am in the world, I am the light of the world.”"