By however a church does it, and churches do it in different ways, what we are actually doing by becoming a formal member is saying “I’m committing myself to you. I’m committing myself to the Lord, and I’m committing myself to you.”
That brings together two really important elements in the Christian life: our faith and trust in Christ and our life for Him; but also our commitment to all those in the fellowship to whom He has committed Himself.
Becoming a formal member of the church is very, very important, because if you don’t do it, in a sense you’re like a child in a family who’s saying, “Well, I don’t think I really want to play with you all.” And when that happens, the parents know something’s gone wrong with the child.
So, actually, not committing yourself to the church—whether formally, informally, or however a church does it—dishonors Christ and, I think, grieves the Holy Spirit.
The other side of it is that it’s only when we do that that the elders and others will feel a responsibility for us. It’s only when we give ourselves to their shepherding of us that they are really able to shepherd us.
It’s also only in that context when people know that we are committed to them. If God has given us gifts, then the space will open up for us to exercise these gifts. There’s no reason why the church should say, “Well, you’re not committing yourself to us, but we really want you to exercise your gifts,” because that would be a denial of our commitment to them and our denial of the love of the Lord Jesus in our hearts for them.
So it’s really of supreme importance.