How Important Is Church Membership (Piper)

I just listened to this sermon by John Piper titled "How Important Is Church Membership".  Here are the quotes I liked:

1) Membership is implied by the way the church is supposed to discipline its members (Matt 18:15-17)... If there is no church membership, how can you define the group you bring this sensitive issue to.

2) Membership is implied by the fact that excommunication even exists (1 Cor 5:12-13)

3) Membership is implied in the Biblical requirement for Christians to be submitted to a group of church leaders (elders/pastors) (Heb 13:17, 1 Thes 5:12-13)

4) Membership is implied by the way the New Testament requires elders to care for the flock in their charge (Acts 20:28, 1 Pet 5:2)

5) Membership is implied in the metaphor of "the body" (1 Cor 12:12-31)

Are you an accountable member of a local church?  I'm not asking is your name on a list somewhere.  Are you committed to discipline and being disciplined.  Have you publically declared your willingness to be lead by a group of elders?  Do you see yourself and your gifts as grafted into a body?