Jesus is both gate and shepherd. Perhaps the significance of this dual image will help us understand progressively where Jesus is taking us. Certainly Jesus wants to provide us with a new destination: heaven. We have to follow Him in order to arrive at that destination. Jesus is also the door however: we must step into him and through him in order to reach the place where He wants to finally lead us.
It shouldn’t surprise us that Jesus acts in different and progressively more direct and intimate ways as we grow in our Christian life. St. John provides us with the seven “I am”s of Christ to introduce us into the mystery of His manifold presence and action in our lives.
Chrysostom:
… When our Lord further on calls himself the door, we should not be surprised. According to the office that he bears, he is in one place the shepherd, in another the sheep. In that he introduces us to the Father, he is the door; in that he takes care of us, he is the shepherd.1
Augustine:
Who is he who enters by the door? It is he who enters in by Christ. Who is he? He is the one who imitates the suffering of Christ, who is acquainted with the humility of Christ, so as to feel and know that if God became man for us, [a] man should not think himself God but man [humankind]. He who being man wishes to appear God does not imitate him who, being God, became man. You are not asked to think less of yourself than you are but to know what you are.2