For the body does not consist of one member but of many. If the foot should say, “Because I am not a hand, I do not belong to the body,” that would not make it any less a part of the body. And if the ear should say, “Because I am not an eye, I do not belong to the body,” that would not make it any less a part of the body. If the whole body were an eye, where would be the sense of hearing? If the whole body were an ear, where would be the sense of smell? But as it is, God arranged the members in the body, each one of them, as he chose. If all were a single member, where would the body be? As it is, there are many parts, yet one body. 1 Corinthians 12:14–20
Church membership is a formal relationship between a Church and a Christian characterized by the church’s affirmation and oversight of a Christian’s discipleship and the Christian’s submission to living out his or her discipleship in the care of the church.