While all believers are members of the body of Christ, there is the issue of each believer’s responsibilities to a local church and its authority in their life through that local body as a whole and its selected leadership as Hebrews 13:7 and 17 teach us, as well as the whole shepherding concept of Acts 28 and the pastoral epistles. In this regard, I believe there are several reasons for membership.
Membership may help to affirm a person’s involvement. It seems to give people a greater sense of belongingness as well as a greater sense of responsibility. Of course, that should come from their walk with the Savior without any such external demonstration as joining a church. Still, it does seem to validate this in people’s minds.
Membership protects the church in the matter of voting on key issues. I have heard of and even been in a situation where people who had not been in the church in years (but were still on the membership role) were brought in to stack the deck in favor of a certain position or issue. Most importantly though, it protects the church against people with unsound doctrinal views or views contrary to a church’s beliefs and Constitution.
Membership can provide a certain amount of protection in legal matters. Today with lawsuits over so many issues like church discipline, it can provide a safeguard. Normally, by signing a membership application or document people are saying they have understood the issues and have submitted themselves to that church, to its doctrine, Constitution, and By-laws, etc. Personally, I think membership requirements should revolve around things like commitment to the church, to its doctrinal beliefs, basic moral issues as clearly outlined in the Word, etc., but should avoid legalistic issues or any coercive elements like promising to give a certain portion of income, or avoiding certain taboos (which always seem to vary with locality). This would entail having a new membership class that all candidates for membership were required to attend before joining. The class should cover the Constitution, but more importantly, the basic beliefs, goals and objectives of the church, and its basic philosophy of ministry (For an illustration see, A Biblical Philosophy of Ministry, on our web site in the “Bible Studies / Pastoral Helps” section).
Membership can be used to acquaint people with the new members by having them come up front to introduce them and maybe by a reception to give people a better opportunity to meet them and get acquainted.
For more information on church membership, you might want to check out, The Nature of the Church, by Earl Radmacher, Western Baptist Press, and The Church in God’s Program, by Robert L. Saucy, Moody Press.