John 17: 21a May they all be one, as You, Father, are in Me and I am in You. (HCSB)
What does it mean to be a "member" of a congregation?
We read of quite a few congregations in the New Testament. Paul wrote two letters to "the church of God in Corinth." Galatians was written to "the churches in Galatia." Romans chapter 16 mentions multiple churches (Gk ekklesias, or assembly). The term "church" referred to the people who assembled together regularly in a particular place. It was obvious who was a part of a particular church. What made a person a member of a certain church was that they were a Christian, and that they assembled with that group.
When a person went from one congregation to another, there seems to have been a practice of sending a letter of recommendation:
Act 18:27 When Apollos wanted to go to Achaia, the brothers encouraged him and wrote to the disciples there to welcome him. On arriving, he was a great help to those who by grace had believed.
1Co 16:3 Then, when I arrive, I will give letters of introduction to the men you approve and send them with your gift to Jerusalem.
2Co 3:1 Are we beginning to commend ourselves again? Or do we need, like some people, letters of recommendation to you or from you?
Php 2:29 Welcome him in the Lord with great joy, and honor men like him,
Col 4:10 My fellow prisoner Aristarchus sends you his greetings, as does Mark, the cousin of Barnabas. (You have received instructions about him; if he comes to you, welcome him.)
3Jn 1:10 So if I come, I will call attention to what he is doing, gossiping maliciously about us. Not satisfied with that, he refuses to welcome the brothers. He also stops those who want to do so and puts them out of the church.
The purpose of those letters was to confirm the fact that the person was a faithful Christian. The letter did not add another requirement for church membership. Diotrephes apparently was refusing to accept some from another congregation who came with a proper recommendation -- and was publicly "called out" for his refusals.
Shepherds need to know who is part of the flock under their care. So there needs to be some kind of communication to let the shepherds know the sheep, and to let the sheep know the shepherds. But what should be the process for accepting a member into a local congregation?
It seems reasonable (and there is biblical precedent) to confirm with the previous congregation that the person is a faithful Christian. But a Christian's "membership" in the congregation should not be contingent upon the leadership exercising that option. It also seems reasonable to explain to the new member what the local leadership expects of all the Christians (Heb 13:17). But again, their "membership" should not be contingent on leadership getting around to having that conversation. As soon as a Christian begins assembling with the rest, he or she is a part of the assembly (aka church.) A Christian should not be expected to jump through hoops to become a member of the local congregation. There should be no probationary period!
Once someone is a member of a congregation, they should be considered a member until they move to another congregation, or until they fall away. If they move, there should be a positive communication with their new congregation to be sure that shepherds there are aware of their new sheep. If a person is showing signs of falling away, multiple persistent attempts must be made to bring them back. A sheep does not cease to be the responsibility of the shepherds when the sheep wanders away! (Eze 34:2-6 Eze 34:12 Eze 34:16
) It is not the responsibility of the sheep to seek out the shepherd. Rather the shepherd is responsible to retrieve the wandering sheep. Wandering sheep are still part of the flock, and are still the responsibility of the flock's shepherds.
The modern concept of church membership is not found in the scriptures. It seems to have been invented to simplify the job of shepherds. But in effect it gives shepherds an excuse not to do an important part of their jobs. I don't think that excuse will stand up on the day of judgment.
Those are my thoughts on the question. I am interested to know how other congregations handle this.