When I took my logic class in school, one of the things that we learned was how to define our terms. One way to define something was to simply point to it and say, "That is it!" This method, of course, assumes that you indeed know what it is that you are trying to define, and that the thing being defined conforms to that definition. This method generally works until you find something that fits the definition, but looks different from what you originally defined. For example, suppose I pointed at a red apple and said, "Apple." That would be quite sufficient until, at least, I came across a green one, and then I might be at a loss. At that point, I need a different method of defining what it is that I was trying to communicate. However, there is always something specific about what it is that you are trying to define that includes everything of that class and excludes everything not of that class.
This is exactly the problem that we run into when those outside of the Lord's church point at us and say, "Denomination!" They see that we have a "church," worship God, have a "pastor," believe in Jesus, study the Bible, meet at about the same time that they meet, have a sign in front of the "church," which bears a name that they see on other "churches," and conclude that we must be something similar to them. "If we are a denomination, then they must be one too," or, at least, that is the kind of thought process I would expect goes through most people's minds when they see our building with our sign on it that says, "CHURCH OF CHRIST." It's not until you really start to look at the churches of Christ that someone starts to understand that there are major differences in how things are done from the way denominations do things. The churches of Christ partake of the Lord's supper every Sunday. The churches of Christ don't use instrumental music. The churches of Christ baptize for the remission of sins. The differences add up eventually. But there is that one attribute that includes all the denominations in the class "denomination," and excludes the churches of Christ from the class "denomination."
Think about this for a moment. When we speak of the term denomination in reference to money, you have the dollar bill, the five dollar bill, ten dollar bill, twenty, fifty, and the Benjamin Franklin. What is it about these bills that makes them a denomination? They are all different, but profess to be of the same kind or class--the class of legal tender. They all bear the inscription, "This note is legal tender for all debts, public and private." Now, suppose that I'm head of the federal reserve and I decide that I want to print another denomination of money. Let's say that I wanted to print up a twenty-five dollar bill. That would be handy. Four of them would make $100.00. So I print up the bills, but I don't put the inscription on the bills. There may be some who would "buy it" so to speak, but most would not take it because it is the belief in that statement, if you will, that makes those denominations valuable. Without the belief in that statement, then the denomination would only be worth the sum of the ink and paper with which it was printed. It would not be able to settle any debts, whether public, or private. That's what makes a denomination of money just that, the belief that it will settle debts. That's the defining trait that excludes it from everything else, and includes it in the class it is in.
So what is that attribute that excludes the churches of Christ from being a denomination and includes all of the denominations within the class, "denomination?" It is the belief, that all "churches/denominations" are all part of the one universal church. That belief can be illustrated with the following graphic, which, by the way, is not original to me. This is the denominational model of the church, which, to be a denomination, one must believe.
You will notice that the largest circle represents the church universal. The medium sized circle represents the denomination, and the smallest circle represents the local church. This is what one must believe in order to be a religious denomination. This is the defining aspect of what it means to be a denomination. This defining aspect includes everyone with this belief, and excludes everyone without this belief. The only problem with this is that you will not find this organization in any part of the Bible. If you want to be a denomination, then this is how you do it.
Now what makes the churches of Christ not a denomination is simply this, members of the churches of Christ do not hold this belief. Just as that twenty-five dollar bill is not a member of the denomination of legal tender. It is the belief in that one defining factor that makes it so. Without that belief, it simply isn't so. Someone might ask, "Well, why do you not believe this?" The answer is really amazingly simple. This belief is not found in the pages of the Bible. The denominational model is completely foreign to the New Testament. There were only two types of organizations discussed within the Bible in relationship to the church. There was the local church, and there was the universal church. There were no denominations under the faith for which Jesus bled and died. You will never find a single one. Moreover, you will never find Jesus or any of his apostles advocating such a situation. In contrast, they advocate absolute unity of the church (John 17:20-23; 1 Corinthians 1:10-13; Ephesians 4:3-6). What is the model for church unity in contrast to the denominational model? There is the universal church and there is the local church. That's all that is there. The following illustration shows this.
This is the model of the church for which Jesus bled and died. This is the model for church unity. We invite all of our friends who may be members of denominations to study these matters. We exhort them to demand the same kind of unity within the church for which Jesus prayed (John 17:20-23) and for which Paul contended (1 Corinthians 1:10-13). We encourage them to search the scriptures to find those things upon which we MUST be united in order to be the Lord's church (Ephesians 4:3-6). The church of Christ is NOT a denomination. There are other differences between churches of Christ and the denominational world, but this is the one key difference that defines what a denomination is, versus what the church of the Bible is. Here is the key to getting beyond that old point and look way of defining a "church" and defining the church in the terms that the Bible defines it in. It starts with this one belief--the unity of the body of Christ based upon what the scriptures authorize her to be. Here is where denominationalism ends and where the church that belongs to Christ, the church of Christ, begins.