The Catholic Church has
infallibly defined the interpretation
of Matthew 16.
The
Council of Ephesus, 431 AD
"No one doubts, in fact, it is obvious to
all ages that the holy and most
Blessed
Peter, head and Prince of
the Apostles,
the pillar of faith, and
the foundation
of the Catholic Church,
received the
keys of the kingdom from our
Lord Jesus
Christ, the savior and redeemer
of the
human race."
When there is error or
misunderstanding, the teaching authority
of the Church is appealed.