Jesus calls Himself “The Good Shepherd” primarily because He gives His life for the sheep. This point is repeated four times in this discourse (vss. 11,15,17,18). From this one simple point we can glean a considerable bit of teaching on the death of Christ.
First we discover that His death was voluntary (vss. 11,17,18). The death of Jesus Christ on the cross at the age of 33 was no tragedy or accident; rather it was planned before the foundation of the world (Acts 2:23). This was the reason Christ was born, as the angel told Joseph, “You shall call Him Jesus, because He shall save His people from their sins” (Mt 1:21). The enemies who brought about His death have no right to boast as if this was their victory.
Second we see that Jesus’ death was vicarious (v.11); that is He died in our place. The Good Shepherd gives His life, for the sheep. You will find this point amplified by Paul in Romans 5:6-8. This doctrine of substitutionary atonement, is the heart of the Gospel – namely that we are sinners, deserving of death, but Christ willingly died in our place, taking our punishment, so that we might be set free from sin and its penalty, death, in order to serve God.
There are several ways in which the activity of the human shepherd compares and contrasts with the action of our Good Shepherd. Consider that though the shepherd may risk his life for the sake of the sheep, his struggle with the wolf, is to save himself with the sheep. This is not the case with Christ who, facing death did not cling to life, but rather laid His life down. Also, while the death of the shepherd results in the death of the sheep, the death of Christ, is the means of salvation of the sheep.