ONE–what a fascinating concept! Strangely enough, it has multiple meanings. Check out part of Webster’s definition (the rest isn’t exactly relevant to our current purposes):
1: being a single unit or thing
3 a : being the same in kind or quality <both of one species> b (1) : constituting a unified entity of two or more components <the combined elements form one substance> (2) : being in agreement or union <am one with you on this>[1]
Can you say God? The word Trinity is not in the Bible, but the plural unity of God is all through the Scriptures. But grasping the reality of this concept is one of the great mysteries of the universe! How exactly is it that three can be one? Have you ever known even two people to be in total harmony at all times and in all things? Even the best of friends are going to disagree at times. But the Father, Son and Holy Spirit have been (and will be) in complete unity for all of eternity.
Can’t comprehend it? Don’t feel bad. For finite humans to totally grasp the infinite Creator of the universe—well, that’s just not going to happen. Truth be told, if God were not graciously willing to reveal Himself to us, we would know absolutely nothing about Him!
How does the unity of the Trinity relate to the unity of the Church? He is the source! What we are is to be an extension of who He is. Unity isn’t something we create. It’s who we are. Anything short of harmony with other believers amounts to tearing down what God has created.
Unfortunately, for many of us the mere mention of the word unity is quickly followed by a torrent of four-letter words such as tolerance (of sin), compromise and ecumenicalism. We picture a fuzzy Kumbaya campfire environment where doctrine is irrelevant and everybody just agrees to get along no matter what you believe.
Let me be perfectly clear. I am not talking about the universal unity of all men or even of all professing Christians. Paul said that the Corinthian church should have had at least some factions (1 Corinthians 11:19) in order to distinguish those who were approved by God from those who weren’t. The problem is that we all think that we’re the only ones approved by God. Somehow we see all others outside of our circle (sometimes that circle includes only one lone individual) as falling short of our standards of rightness.
This self-aggrandizement is at the heart of our problem. We judge and tear down other members of the Body of Christ because they are not as right as we are. If we are so right, then how can we be so judgmental? If our doctine is so perfect, why are we so stone-hearted? How is it that we are so unloving toward Christians from other organizations? If our doctine really is so perfect, we wouldn’t be tearing down the unity of Christ’s Body.
Surely some very personal changes are in order!
(Chapter 8 of my Search for Me Identity Series address this issue in more detail. It is free to stream online.)
[1] http://www.merriam-webster.com/dictionary/one – accessed on 3/16/11
Hidden Trails 
So true, Bob. Sometimes the problem is an attack of others for a specific (we think justified) reason. Sometimes, however, I think the situation is that we get so comfortable with the people we’ve known for years, and we end up thinking, talking, and acting alike. “Outsiders” are just…different, maybe neither better nor worse, but definitely…different. People I’m not comfortable getting to know and fellowshiping with because they don’t know how I like to do things. How different it will be in heaven, and when we reign with Christ, because HE will be the focus and not ourselves! Thanks for your thoughtful and insightful posts!
Paula, your thoughts about “different” really strike a cord with me. Well said!