“Only let your manner of life be worthy of the gospel of Christ, so that whether I come and see you or am absent, I may hear of you that you are standing firm in one spirit, with one mind striving side by side for the faith of the gospel…
…complete my joy by being of the same mind, having the same love, being in full accord and of one mind.” —Philippians 1:27, 2:2
Unity isn’t a collection of helium-filled balloons, held together only by strings in a hand swinging playfully about. Unity is like the wall of a stone fortress, rooted in the earth, prepped for battle. Unity isn’t a thing you play with; it is something you fight with. I fear that when the church preaches and pursues unity, she goes for fun and floaty balloons rather than an anchored and strong fortress, and balloons are so easily popped.

Mark Dever has said that what you win them with is what you win them to. A self-evident corollary of this, though perhaps not as catchy, is this: what you unite your people with is what they are united by. That’s a bit of a tautology, but unfortunately the obvious is only obvious to us as an equation. Weak glue is easily broken. “Man” as a glue is like using Elmer’s for mortar in a stone cathedral. Much church “unity” is nothing more than children gathering around some shiny new balloons. If you want to break it up all you need is a pair of scissors. Further, Helium is faddish. As the balloons fall the crowds disperse. Cue the creative clowns to continually twist things to the people’s delight.
The major problem is that man is trying to create a unity instead of working out and living according to the unity that God has created. Richard Philips has said that perhaps the best way we can deal with the alleged problem of unity is to deny that there is one. The saints have long confessed that the church is “one, holy, catholic, and apostolic.” After commending the Ephesians to be “eager to maintain the unity of the Spirit in the bond of peace,” Paul goes on to say that “There is one body and one Spirit—just as you were called to the one hope that belongs to your call— one Lord, one faith, one baptism, one God and Father of all” (Ephesians 4:3–4, emphasis mine). God is the only glue that can hold the church together. By Christ’s blood we are mortared.
It is critical then, that as you read Paul’s call for unity in Philippians, you realize that these commands don’t float. They are anchored. The gospel is their source, the gospel determines their shape, and the gospel is their purpose. Unity is by the gospel, in the gospel, and for the gospel.
To me of the major tragedies of the hour, and especially in the realm of the church, is that most of the time seems to be taken up by the leaders in preaching about unity instead of preaching the gospel that alone can produce unity.
If all the churches in the world became amalgamated, it would not make the slightest difference to the man in the street. He is not outside the churches because the churches are disunited; he is outside because he likes his sin, because he is a sinner, because he is ignorant of spiritual realities. He is no more interested in this problem of unity than the man in the moon.” —D. Martyn Lloyd-Jones