Matthew 16:18

In the original Aramaic context, the wordplay is seamless: 'You are Kepha, and on this kepha I will build my church.' The Aramaic 'kepha' means rock and is both the name Jesus gave Simon and the foundation of the community. The original hearers would have understood a direct connection between Peter and the rock without the grammatical distinction that exists in Greek between 'Petros' (masculine) and 'petra' (feminine).

Chrysostom, representing the Antiochene school, interpreted 'this rock' as Peter's confession of faith ('You are the Christ, the Son of the living God'), not Peter's person. He argued that Christ built His church on the faith that Peter expressed, which is the foundation shared by all believers. This became the dominant Eastern Orthodox interpretation and later influenced Protestant readings.

Medieval Western theology, building on Leo I and Gregory VII, read this verse as the foundation of papal authority. 'Upon this rock' meant Peter personally, and his authority was transmitted to his successors as bishops of Rome. This interpretation undergirded the entire structure of medieval Christendom: the Pope as Vicar of Christ, possessing the 'keys' (v. 19) to bind and loose with universal authority. The Petrine primacy was considered divinely instituted and unalterable.

Calvin rejected the papal interpretation, arguing that 'this rock' referred to Christ Himself (citing 1 Corinthians 3:11, 'no other foundation than Jesus Christ') or to Peter's confession of faith. He noted that Peter himself called Christ the cornerstone (1 Peter 2:4-8). Calvin argued that even if Peter were the rock, this granted no transferable authority to Roman bishops. He emphasized the 'keys' were given to all the apostles (Matthew 18:18, John 20:23), not Peter alone.

Contemporary scholarship generally acknowledges the wordplay identifies Peter with the rock but debates its ecclesiological implications. Oscar Cullmann's influential study argued Peter had a unique foundational role in the early church that was historically unrepeatable, not transferable. Catholic scholars after Vatican II (like Raymond Brown) recognize the verse does not directly address later papal structures. Protestant scholars increasingly accept Peter's special role while denying papal succession. Ecumenical dialogue has made this less of a battle line and more a point of constructive conversation.