The Spirit of God keeps the door of the sheep. Christ, as serving the Father, enters the door. From now on Christ Himself is seen as the door of the new fold. He gives the authority to leave the old Jewish economy and enter into the new order of salvation — believing on and following the Shepherd, who is Christ. The sheep are familiar with the voice of the Shepherd, and He calls each by name.
Christ enters by the door. He is the door; He is the Shepherd. He is seen in contrast to all previous shepherds. The sheep, confined to the Old Testament order of the law and the traditions of men, are ready to accept an entirely new order of things — an order which brings, rather than requires (like the law) something of man. Christ, being the door, is the only way of entrance into the new fold. When He presented Himself as the door, the Jews whom the Lord was addressing did not understand His words. The elect of Israel readily accepted salvation full and free. Those who entered in by the door were saved, enjoyed liberty, and fed in good pasture.
C. E. Lunden