λέγω δὲ τοῦτο ὅτι ἕκαστος ὑμῶν λέγει· ἐγὼ μέν εἰμι Παύλου, ἐγὼ δὲ Ἀπολλῶ, ἐγὼ δὲ Κηφᾶ, ἐγὼ δὲ Χριστοῦ. μεμέρισται ὁ Χριστός; μὴ Παῦλος ἐσταυρώθη ὑπὲρ ὑμῶν, ἢ εἰς τὸ ὄνομα Παύλου ἐβαπτίσθητε; (1 Cor. 1:12-13)
But I say this: that each of you say, I am of Paul, and I am of Apollos, and I am of Cephas, and I am of Christ. Has Christ been separated? Was Paul crucified for you, or was it into the name of Paul you were baptized? (1 Cor. 1:12-13; my translation)
Last Lord's Day, I had the privilege of bringing God's Word to the saints at Providence Reformed Presbyterian Church, which can be heard here.
It is very easy to take the moralistic route on this passage and just preach that the church must be united, as if unity in the church is as easy as having a big campfire and everyone holding hands and singing around the campfire. But to do justice to the text, one must deal with the real issue of the ground of unity, which is the Gospel message. The problem and sin of schism is real, but more laws and commands will not be able to solve it. We notice here that there are 4 factions under 4 figureheads that Paul mentioned: "of Paul," "of Apollos," "of Cephas or Peter," and "of Christ." The first faction focus on evangelism and church planting, the second emphasizes Bible study, rigorous intellect and apologetics and the third faction, history and tradition. Notice here that the fourth faction claim to be above the fray. In my sermon, I point that those who cry "no creed but Christ," the non-denominational denominations (which I did not name in my sermon, but people can look at examples like the Christian and Missionary Alliance or Calvary Chapel) and anti-intellectuals will fit that category. I will here further point out that striving for "unity" on grounds other than the Gospel will also fit into this category, since such is essentially putting up a new law for believers to keep.
The problem of unity is not that no one wants unity, but that everyone wants unity on his terms. Even the so-called modern "ecumenical movement" is essentially the 4th faction, since they think themselves above the fray of denominational differences while uniting around a social gospel and not the true Gospel itself. True biblical unity, if it is to be there, can only be found in the true Gospel. It stands to reason therefore that anyone, any church, and any denomination that denies the Gospel has cut itself away from true biblical unity. That is why the "ecumenical movement" manifests a false demonic unity, since the Gospel is not the center in it but only a perversion thereof.
True biblical unity therefore is hard, because it requires fidelity to the Gospel, an understanding of its centrality, and an understanding of the subservient functions of other biblical doctrines (baptism in the case of the Corinthians). Christians seeking true biblical unity should strive for it, which in the biblical Presbyterian model imply that they ought to be seeking to join local churches into presbyteries, synods and General Assemblies. This should be the goal for Christians to strive towards, a truly difficult task at hand.