Membership in a local church defines who is identifying with that group.
It is important that we prayerfully choose to commit to a local church, invest in it and be invested in, serving together with others to carry out God's purposes and plans.
A willingness to be mutually acountable with others is an essential characteristic for members of a healthy church.
As believers fellowship together, identify with each other, and commit to stimulating each other to love and good deeds, that maturity will develop in them.