Why be a church member? Why not just be able to go and participate?
I think the answer is that you should be a church member. But that's not even a clear word—what does "member" mean?
What I mean by "member" is somebody who, whether by a signature or a word of commitment or promise, says, "I'm committed to a people, a people who hear the word of God preached, a people who perform the ordinances that Jesus gave to his church (baptism and the Lord's Supper), and a people who commit to the 'one another' commandments (love each other, exhort each other, admonish each other, hold each other accountable)."
Those commitments are what membership is. And I think something is wrong if you resist putting your name on the line for that.
If you want to say, "OK, I believe the New Testament says, 'Be a part of a community, give yourself to ministering there and receiving ministry there, and advancing the cause of the gospel there, and upholding the name of Jesus there, and doing mission there,' and I'm a part of that," then to resist putting your name on the line for that is probably not a biblical conviction. It's probably an American, independent, give-me-elbow-room, don't-get-in-my-face-too-often conviction, which I don't think is biblical.
The reason for even using the word "member" is because of 1 Corinthians 12-14, where Paul uses the word "member" in a body analogy.
The local church—not just the global church, but the local church—is a body. The reason we know it's local and not just global is because, while in Ephesians 1 and Colossians he talks about Christ as the head of the body, in 1 Corinthians 12 he's talking about a head with eyes and ears that are members of the body.
So the body analogy has one global meaning, and it has one local meaning. There's global membership in the body universal, and there's local membership in the body where I'm a finger or an eye or an ear or a foot. And everybody is a member.
So the word "member" in 1 Corinthians 12-14 means you're part of a local organism, and the finger belongs. It should care about what happens to the eye, and the eye what happens to the finger. And it should function in a way that has some organic coherence to it.
It's very hard to do what the Bible calls a church to do unless it knows who are the members and who aren't. Who are the people that want to be treated as members here?
A very simple example of this is the biblical concept of church discipline.
In 1 Corinthians 5, for example, Paul says that the man who is sleeping with his mother-in-law (or stepmother) should be put out of the church because he is so proud and arrogant about his sin, and unrepentant and resistant to any kind of exhortation. But how can you put him out? He could just say, "I just go here! They can't put me out of anything. I'm not in anything!"
And I think a lot of people don't want to be in anything because they don't even like the idea of being able to be put out of something.
So for all those reasons, even though there's no sentence in the Bible that says, "There is such a thing as church membership, and thou shalt be a church member," I think it's implied in the nature of the church and of Christian discipleship that everybody should, by a covenant commitment of some kind, put their name on the line saying, "I'm here. While I'm in this place, and until God leads me otherwise, these are my people and I'm committed here."