The words we use and the way we use them show other people both how we think and what we think about. Words are very powerful, so much so that they affect the way we act. This is true in all aspects of life, including the church.
When you hear the word "church," what do you think about? Some folks immediately think about a building. Others immediately think of the group of Christians they gather with a few times per week. Others think about the universal church of all believers. Still others think of the church as being something that falls somewhere in between either two or all three of the above.
How we think of, talk about, and describe "church" will greatly affect how we live out our Christian lives. In other words, how we describe what the church is and does will impact what we do.
For example, if we primarily think of the church as a building, we will necessarily focus much of our attention on the building itself. We will probably care a great deal about how the building looks, how clean it is, and how it is used by strangers. Much of our time and effort will be aimed at the edifice itself.
If we primarily think of the church as a local group of believers, our focus will be on that group of believers. We will spend much time together, meeting regularly and taking care of one-another's needs. Much of our time and effort will be aimed at when we gather together. We will probably care quite a bit about denominational differences.
If we primarily think of the church as the universal church of all believers, our focus will be on all Christians, regardless of what local church they are a part of. We will spend much time with followers of Christ. They may not gather with us during the week, but we still have active fellowship with them. We will probably have less of an "us-and-them" attitude and care less about denominational differences.
I realize that I have not addressed the issue of how Christians should interact with those who do not know Christ (that would make for a post that is longer than any of us desire to read right now. Share Christ with them and love them).
The above 3 categories of church definitions are not as precise as I would like, but they serve a purpose. If we want to be as biblical about the church as we can be, we must lean toward the universal church model. This appears to be what we see described in scripture most frequently. Some would argue this point, saying that the local church is what we most often see. My response to that is that the local church should be a manifestation of the universal church. When we draw a dividing line between the local church and the universal church, we are creating a division that does not appear in scripture.
Of course we should gather with a local body of believers. However, let's avoid any kind of us-and-them mentality toward other followers of Jesus Christ. One way we can do this is by being careful how we think and speak about the church. When we ponder what the church of God is, it clearly is not a building. We should banish that thought from our minds.
God's church does take the form of many local congregations. However, these bodies ought not have strong dividing lines between themselves and others groups of believers. We are all part of the same group that will be living together for eternity in the New Jerusalem.
Let's all try to be careful how we think about church. Let's strive to be as biblical as possible. How we think and especially how we speak about the church will affect how we live out life in the church.