This is an oldie but a goodie: The Scriptural Language of Membership . Alan Knox looks at the passages containing the word "member" that are often (mis)used to insinuate some sort of system of formal church membership. The traditional use of formal membership, as I have written numerous times before, is nothing more than a method of controlling people, of exerting power and authority in a misplaced manner that usurps the Kingship of Christ. Because it is so deeply entrenched in the cultural understanding we have about the church, the powers that be and those with a vested interest in sustaining the system defend it by any means possible, including outright misrepresentation of Scripture to meet a preset agenda. This should not be so.
When you are born again you become part of the Body of Christ, united with Him by adoption and united with every single other Christian without restriction or differentiation. That union doesn't depend on membership classes, or votes or affirmation by anyone other than Christ and it cannot be controlled or revoked or limited by anyone else. If we say we love one another but only on our own terms we make a lie of the great commandment and a mockery of everything the Bible teaches us about the church.