They may “exist” for those purposes, but SHOULD they? The unity of the one and only Body of Christ does not depend on philosphical or theological agreement. That unity is contingent on discipleship. If we are submitted to the authority of God’s Son and Messiah Jesus, then we are unified in the only way that matters. Emphasizing doctrines (whether true or false) is what divides Christians.
I used to meet with the so-called “Plymouth Brethren”. (I would probably still do so, if there were any in my area). As I remember, they met in the name of Jesus alone, and any brother in the assembly could minister. Actually they were non-denominational. But assemblies who are expressions of the one and only Christian Church are given “denominational names” by others since many can’t seem to fathom that churches can be expression of the Church without being denominational. That particular group was given the name “Plymouth Brethren” because they first met in Plymouth, England.
I have met with two other expressions of the Christian Church including the one with whom we are now meeting. Such groups are disctinctive in the following ways (I recognize that there is overlap in some groups, that not all of these neatly fit into one or the other. I am but expressing tendencies which I have observed)
Church Membership
Denominational Groups: You must join and be on a membership roll in order to enjoy full privileges. (similar to the requirements of other clubs)
Expressions of the Church: Anyone who is a disciple of Christ is a member of the only Church there is, and has full privileges in local gatherings.
The Ministry
Denominational Groups: In smaller assemblies, there is usually a single “minister” or “preacher” or “pastor”. He/she normally does all the preaching, visitation, dealing with problems, etc. In larger assemblies, there may be one or more “assistant pastors”.
Expressions of the Church: There is a “body ministry”, that is, each member may offer a psalm, a hymn, a teaching, etc. in the assembly as the spirit of God leads. There are elders and deacons, but they do not necessarily do the speaking. Anyone present may do so as the Lord leads.
Church Government
Denominational Groups: There are a variety of forms. Some denominations (e.g. Baptists) have a democratic form of government, led by “deacons”, though final decisions are made by democratic vote of the members. Other denominations have a “presbyterian” form of government where a board of elders make the decisions. Still others have an “episcopalian” form of govenment where the regional bishops have the last word.
Expressions of the Church:
There are local elders who rule the local churches, who are assisted by deacons, but input from the people is always welcomed when it comes to decision making. Expression of the Church are not democracies. Their aim is to be a theocracy where God rules.
Function of the People:
Denominational Groups: The people are expected to sit in pews as an audience, facing a platform at the front listening to the pastor or to the choir. In many churches, the sermon is the chief feature.
Expressions of the Church:
The people are expected to participate in all aspects of the ministry. In many expressions, the people sit in a circle in order to better minister to each other and to receive ministry from others.
Problem Solving:
Denominational Groups: In small assemblies, the pastor is consulted as the problem solver. In larger assemblies, there may be a psychiatrist or other official to handle such matters. If there is a physical need, the person may be directed to a professional or to a government agency.
Expressions of the Church:
The elders are often consulted, but they are pleased when other members also help those with personal problems. Often several or many members of the Body help to meet physical needs by contributing their time and money.