when Jesus says,
“You are ‘Cephas’, and on this rock I will build My Church,”
He isn’t speaking Greek, He’s speaking Aramaic. In Aramaic, the word He uses is Kepha, which means rock. So His original words were:
“You are Kepha, and on this Kepha I will build My Church.”
Unlike Greek, Aramaic makes no distinction between petros (small stone) and petra (large rock). That distinction only appears later in Greek translation, where grammar required the masculine form Petros for Peter’s name.
In other words, Jesus didn’t call Peter a “pebble.” He called him the rock, the same word in both clauses, on which His Church would be built. Any supposed ambiguity arises only from translation, not from what Jesus actually said.
This understanding is entirely consistent with what the earliest Christians believed. But under Sola Scriptura, the interpretation of Ignatius of Antioch, a disciple of the Apostle John, ends up carrying no more weight than Bob from the post office.