Andrew knew Jesus was the Christ before Simon did: “He findeth his own brother Simon, and saith unto him, We have found the Messias, which is, being interpreted, the Christ. And he brought him to Jesus. And when Jesus beheld him, he said, Thou art Simon the son of Jona: thou shalt be called Cephas, which is by interpretation, A stone.” John 1:41,42
“A stone”, not THE stone.
The stone that the builders rejected is become head of the corner. Peter himself declared that Jesus Christ is the chief corner stone of the church.
Andrew knew that Jesus was the Messiah, the Christ.
But that isn’t what Peter said. Peter called Jesus the “Son of the living God.” It was that confession that prompted Jesus to give Peter the keys of the kingdom.
Does the distinction between “a” and “the” even exist in Aramaic and/or Greek? I doubt it.
You have been propagandized.