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.***