Unlike today, in the early church, when you became a Christian it inherently meant you went to church. It is simply assumed in the way the New Testament and early church documents are written. You became a Christian... you went to church. It followed naturally. There was no "me and my private relationship with God over here in my little corner" that we see today. It just didn't happen like that.
The church is sometimes called a flock, and the elders (leaders) shepherd the flock. And the shepherd needs a way to know which sheep are in his flock in order to care for them. He's responsible before God for the flock that has been entrusted to his care, and so he needs to be very clear which sheep belong to him. Hebrews 13:17 says "Obey your leaders and submit to them." What leader is going to claim any kind of authority over random people, and what random people will submit to that? There is assumed some kind of clear understanding and knowledge of who is submitting to whom. In one letter it says "when the whole church comes together...". How would you know if the whole church was together unless you knew in some clear way who was supposed to be there?
There are so many examples of exhortations that include the phrase "one another", most notably Hebrews 10:24-25, "And let us consider one another in order to stir up love and good works, not forsaking the assembling of ourselves together, as is the manner of some, but exhorting one another, and so much the more as you see the Day approaching." It is clear this isn't just some loose affiliated bunch of floaters that are uncommitted to one another. They are described as a body, a family, a flock, and a household, knit together as one unit.
If you'd like more justification for the necessity of church membership, you can go here for a Biblical basis of church membership, here for an article entitled "Is Church Membership Optional?", or here for an article from my church in the US on the topic.
And so, wanting to be in line with Scripture, last fall we started down the road towards Church Membership. We had several weeks of teaching on the subject to help everyone clearly understand various aspects of The Church and the importance of membership, and then we accepted applications and spoke with each individual who applied. A few weeks ago we welcomed the first members of Eclesia International Church, and it was a joyous night indeed. A total of 35 people were inducted this time around, we expect that another 5-10 will apply for another round in April. Elders from our sister church asked us a few basic questions that we publicly answered together, and then they prayed for us. No "magical" formula or anything, just a simple step of obedience as a congregation and as individuals.
At the end of every choir rehearsal we sing a little song together that has become so very dear to me and comes to mind now as I write:
I love this family of God
So closely knitted into one
They've taken me into their hearts
And I'm so glad to be
A part of this great family
I am indeed so glad to be a part of the family of God, thankful to be a daughter of the the King of heaven, and united in fellowship with all those who accept the free gift of salvation offered by Jesus. And while we've certainly been a family and a church for a long time, it's such a wonderful step to be officially committing to church membership together. I am most grateful to be a part of this piece of the family of God for this season of life.