Unity should be evident in the way Christians talk to and about one another, in forbearance and forgiveness, in fellowship of psalms, hymns, and spiritual songs. It involves a recognition of our brotherhood in baptism and a practice of table fellowship. It is a unity in faith, in life, in practice, in water and bread. An invisible unity is not a biblical unity. Visible division is incompatible with the New Testament’s portrayal of the church.
– Peter Leithart, The End of Protestantism: Pursuing Unity in a Fragmented Church, p. 21 (emphasis added).