Peter’s choice of the upside-down cross was the truest symbol of unentitled devotion because he refused to exalt himself even in imitation of Christ, thus representing His completely self-denying identity. The only response of a true disciple when confronted with the cross of Christ is to lose all sense of pride in your own glory, to release your earthly expectations and take up your cross and follow Him in the pattern of unconditional lay-down-your-life love.
God first had to destroy the “chosenness” of the entitled Jews so that He might establish the chosenness of grace for the entire world in its place. That’s why John writes that God “came to His own, and those who were His own did not receive Him,” referring to the Jews. “BUT as many as received Him” – Jew and Gentile – “to them He gave the right to become children of God, even to those who believe in His name, who were born, not of blood, nor of the will of the flesh, nor of the will of man, but of God.” (John 1:12) This “right” is the new covenant, which is the chosenness of GRACE which is sealed by the blood of Christ and obtained through faith.