NOTES for Mat 16:13-19
Peter stands out among the other disciples of Christ not only by age and by leadership traits. But all of that is not enough for the astonishing promise that Jesus gives him (Matt. 16:18). Perhaps Peter's most important quality, the one that makes him the second most significant figure in the Gospel, is that he responds immediately and actively to every new situation in his relationship with Christ. He hardly pauses to think and often makes mistakes, but he is not passive; he makes the effort. It is Peter who tries to walk on water, and it is Peter who becomes the first of the disciples to perform miracles of healing and resurrection.
Of course, there are other paths of holiness, but Christ lays Peter's holiness at the foundation of the holiness of the Church.