This is a healthy meditation when looking at the (sometimes splintered) unity of the church. If someone says to me, “Well, what about your million denominations?” The best response is, “And?”
For us, the unity of the Christian Church has never been manifest except in her marks, in the same way that the divinity of Christ, during His humiliation, was not manifest except in His marks. The cross marked Jesus, as could nothing else, as the Christ, the King of the Jews.
Perhaps an insistence–perhaps an ahistorical one at that–on outward unity at all costs is itself reflective of a theology of glory, not a theology of the cross.