Matthew 16:18 — "Upon This Rock"

The Plymouth Brethren adopt a nuanced Protestant interpretation of Matthew 16:18, understanding the "rock" not as Peter the person, but as either Christ himself or Peter's confession of faith. This reading allows them to affirm Peter's faith and role without conceding papal authority or apostolic succession—doctrines they reject as unbiblical additions to Scripture. The shift from Peter (Greek Petros, masculine) to rock (petra, feminine) is interpreted as a grammatical hint that the building foundation is not the apostle but something more ultimate.

Many Brethren commentators have pointed to 1 Corinthians 3:11 and Ephesians 2:20 as clarifying texts: Christ is the true foundation, and the apostles (plural) lay the foundation of the Church—not one apostle above the rest. J.N. Darby's biblical commentaries emphasize this corporeal apostolic foundation and Christ's headship of the church, rejecting hierarchical ecclesiastical structures. The Brethren stress that Peter remains a servant of the word, subject to Scripture like any believer, and that no single leader holds keys to the kingdom.