In a time of outspoken atheism and decreasing religious affiliation, Christians might be tempted to highlight the distinction between those who believe in God and those who don't. On first glance, this approach seems helpful. At work the believers know who they can greet with "Merry Christmas"or "Happy Holidays," while students know who to group up with to discuss the new Hillsong CD. While I'm all for Christians encouraging one another, and for avoiding needless confrontation as we seek to be good neighbors (Rom 12:18), on closer inspection this distinction actually misses a more important one: those who love God and those who do not.
For one, Scripture indicates that, in one sense, belief is a relatively insignificant factor in determining one's standing with God. As James puts it, "You believe that God is one. You do well; the demons also believe, and shudder" (James 2:19). In other words, if we maintain a spreadsheet exclusively divided between "belief" and "unbelief," the demons go under "belief." That's not helpful.
The more important category is "Those-Who-Do-Something-With-Their-Belief," or those people for whom belief takes root and overflows into a life of devotion to Christ. They are those who love Jesus and "keep his commandments" (John 14:15). Indeed, "this is the love for God, that we keep his commandments" (1 John 5:3). More significantly, it is not only those who do not believe who are condemned (as the belief vs. unbelief distinction might imply). Paul puts a fine point on it: "If anyone does not love the Lord, he is to be accursed" (1 Cor 16:22). Let us not delude ourselves into thinking that mere belief is enough; "faith without works is dead" (James 2:26).
One Warning: If we were to change the way we think by shifting from belief to love as the distinguishing characteristic between the church and the world, we would have to face a startling reality, some of us may find ourselves in an unexpected column. Lord, help us love you, "not with word and talk, but in deed and truth" (1 John 3:18).