Heidelberg Catechism, Lord’s Day 21, Question and Answer 55 professes “the communion of the saints,” by which we mean that “each member should consider it a duty to use [their] gifts readily and joyfully for the service and enrichment of the other members.”
The Belhar Confession, Section 2 testifies that the unity of God’s children becomes active “in a variety of ways; in that we love one another, that we experience, practice and pursue community with one another...”