This is a fair question and one that deserves an answer. The phrase comes from Romans chapter 16 verse 16. This speaks of the Lord's people in the New Testament days as a congregation. First Corinthians 14:33 uses the phrase "churches of the saints" in the same sense. There are many descriptions given: church of God, churches of Asia, Galatia, gentiles, the bride of Christ, church of the Firstborn, the church of the living God, etc. The Bible is plentiful in its descriptions but more often than not the term, "the church" is simply used to describe God's people.
The word for "church" simply means the "called out". When people today mention a church we have to say, "which one"? Not so in the Bible. The churches of Christ are the same today as they were in the New Testament, non-denominational, undivided (First Corinthians chapter 1 verse 10), of single heart and mind (Acts chapter 2).
Our only guide is the Bible, and specifically, the New Testament. Our allegiance to this book finds Christians all over the world following the same rule of faith, and thus practicing and believing the same things. The very nature of denominationalism is that of division which is certainly not what God had in mind for His people. It is possible to be of one mind and of one spirit if we determine to follow God's clear directions and put away the rules of men.
The Bible is not unclear about what man must do in order to be saved. Should the Lord's people be divided on such a key point? And yet different brands of churches teach a whole host of answers to this simple question. Some will stop short of what is required by the Lord and others will substitute their own plan for that which is plainly revealed in the New Testament. If our God is not divided on this issue then neither should those who intend to serve Him. In fact, they are not. For if we ignore what God says about responding to our sin and the cross of Jesus, we are not God's people at all.
It is our aim to honor the Lord of Heaven with all our might by honoring the terms of His inspired Word. The New Testament ONLY makes Christians ONLY. But today we have some who call themselves "Baptist-Christians" or "Methodist-Christians" or "Presbyterian-Christians", etc., etc. When we add a little bit (or a lot) of man's ideas to what God has said we end up with another denomination, another segmentation in the religious world, another church. Do we really need another church? We are saying what God provided in the apostles' time is not adequate if we answer yes to that question. If we will simply get back to the Bible we will be simply Christians. And that is what God intended for the church. If we will do that we will be the same church of Christ that existed 2,000 years ago. The New Testament had Christians only, in Heaven there will be Christians only, the churches of Christ are Christians only. What kind of Christian do you want to be?
--David N. Powell