To understand how and how often to eat the Lord's supper we must understand what kind of book the Bible is. Is it just history? Is it just devotional inspiration? Is it a guide, a pattern? If the latter, what in it must we follow?
The Bible teaches in ways other than direct statements and commands. Paul said, "Be ye imitators of me. For this cause have I sent unto you Timothy...who shall put you in remembrance of my ways which are in Christ Jesus" (I Cor. 4:16 -17). From this we learn that the Holy Spirit, directing Paul, expects us to learn by example, as well as by commands. We are to imitate the ways of Paul. Not all his ways, just those that are in Christ, those having to do with how he served Christ. And his examples are to be followed alike by all the congregations (I Cor. 4:17 ). Similarly we read, "The things which ye both learned and received and heard and saw in me, these things do" (Phil 4:9). By showing us how real people and real churches in real history acceptably served Christ, Jesus says, "Here is how I want to be served. Serve me as the people did who were directed by the apostles."
Now we go to Acts 20:7 and find: "Upon the first day of the week, when the disciples gathered together to break bread, Paul preached to them." Paul arrived there on Monday. So in spite of the fact that Paul was hastening to Jerusalem , he tarried until the first day of the week when the saints would meet to break bread (eat the Lord's supper, I Cor. 11:26 ). Some read this and say, "So what, they ate the Lord's supper on the first day of the week. What does that have to do with us?"
Remember, the Lord teaches us by the examples in his word. So when we ask how often the church meets to eat the Lord's supper, the only information is an example telling us brethren met to eat it on the first day of the week. And the hastening Paul waited until then to eat it with them. They would not be coming together to do it sooner or at some other time. So we eat not just following a casual event, but a purposeful apostolic example. Since the Lord said he wanted us to learn in that way and follow, we take this precedent as instruction, and eat the Lord's supper on the first of the week, not neglecting any. If we decided not to eat the Lord's supper on some Sunday, then we would not have eaten it on the first day of the week according to precedent.
We eat one bread, which is a communion of the body of Christ (I Cor. 10:17 ). There is a unity of our eating, unleavened bread. We drink one cup which is a communion of the blood of Christ. There is a unity of our drinking, fruit of the vine (I Cor. 10:15 -16). The one cup is not the container. The word "cup" is a figure of speech known as metonomy, where the contents are referred to as the container. We say the baby wants a bottle. Lots of luck. Hand the baby just the glass container and he will continue to cry. We drink one cup, the contents. We all drink the fruit of the vine, representing the one thing, the blood of Christ. You will not find some drinking orange juice, others tea. At the passover meal, Jesus instituted the Lord's supper. He took a cup and told them to divide it among themselves. They didn't fragment the container. They divided the contents. Then they ate the bread and drank the cup which was already divided among them (Lk. 22:17-20; I Cor. 11:23-27). Drinking the cup, they evidently used several containers, having divided the cup among themselves before drinking. -- Dale Smelser