What is the Biblical basis for the formal 'membership' requirements that some Baptist churches have? When I have been looking for a church to congregate, I have found that there are different ideas about membership. Some churches require a letter of transfer. Other churches need to see my behavior for a while. I must sign and agree with the distinctives and the statutes (a set of rules or responsibilities). I've come to think that is too much of a bureaucratic process. Some people say that as a member, you can participate in the decisions of the church.

Where does the Bible support the concept of membership?  Where is it indicated that this is how things were in the first century church?

Note: A Baptist perspective is sought.
In 1 Corinthians 5:12-13 Paul says


  12 For what have I to do with judging outsiders? Is it not those inside the church whom you are to judge?  13 God judges those outside. “Purge the evil person from among you.”


Church membership is how we know who is and isn't a believer. The church, as a whole, is charged with the task of declaring who is and isn't a believer based on their testimony. In Matthew 18:15-17 Jesus gives another example of the church having members:


  15 “If your brother sins against you, go and tell him his fault, between you and him alone. If he listens to you, you have gained your brother. 16 But if he does not listen, take one or two others along with you, that every charge may be established by the evidence of two or three witnesses. 17 If he refuses to listen to them, tell it to the church. And if he refuses to listen even to the church, let him be to you as a Gentile and a tax collector.


How are we to know who is or isn't a believer if we don't have membership? The ability to exclude someone from the church means that there was also inclusion/membership/a group defined as "the church". Here are a couple other verses to consider when thinking of church membership:


  Acts 5:12-13: “Now many signs and wonders were regularly done among the people by the hands of the apostles. And they were all together in Solomon’s Portico. None of the rest dared join them, but the people held them in high esteem.” 


So, people faced the decision of whether or not they would join the church in Jerusalem. 

This joining is more public and definite than an informal association.

2 Corinthians 2:6: Paul talks about a man who had been excommunicated, 


  “For such a one, this punishment by the majority is enough, so you should rather turn to forgive and comfort him, or he may be overwhelmed by excessive sorrow.” 


A majority can't have decided on the exclusion unless there was a definite set of individuals who could make that decision as a church.