The third and fourth “I am” statements go together sense both speak about Jesus caring for His sheep. The sheep are those to whom He was speaking to in each event.
The third “I am” statement recorded in John is in chapter 10. In verse 9, Jesus says, “I am the door.” This statement follows the Good Shepherd proverb. It is likely that Jesus had contrasting images of Zechariah 12 in mind as He spoke the proverb. Zechariah 12:10 says,
“. . . the Spirit of grace and of supplication, so that they will look on Me whom they have pierced.” On one side is the worthless shepherd who deserts his flock and on the other is the shepherd who is stricken for the sake of the sheep, publicly pierced and eliciting great mourning and grief. When Jesus says, “I am the door,” he is saying that He is the only means the sheep enter life; there is only one entrance into a sheepfold so Jesus was using what the people knew. Jesus is saying that He is the only way into life; He alone is the door.
Following on from the conversation about being the door, the fourth “I am” statement is in verse 11 of John 10. Jesus says, “I am the good shepherd.” The idea of Jesus being the ‘good shepherd’ goes with what the prophet Ezekiel says in Ezekiel 34. Ezekiel 34:12-24 says,
“12 As a shepherd cares for his herd in the day when he is among his scattered sheep, so I will care for My sheep and will deliver them from all the places to which they were scattered on a cloudy and gloomy day. 13 I will bring them out from the peoples and gather them from the countries and bring them to their own land; and I will feed them on the mountains of Israel, by the streams, and in all the inhabited places of the land. 14 I will feed them in a good pasture, and their grazing ground will be on the mountain heights of Israel. There they will lie down on good grazing ground and feed in rich pasture on the mountains of Israel. 15 I will feed My flock and I will lead them to rest,” declares the Lord God. 16 “I will seek the lost, bring back the scattered, bind up the broken and strengthen the sick; but the fat and the strong I will destroy. I will feed them with judgment. 17 “As for you, My flock, thus says the Lord God, ‘Behold, I will judge between one sheep and another, between the rams and the male goats. 18 Is it too slight a thing for you that you should feed in the good pasture, that you must tread down with your feet the rest of your pastures? Or that you should drink of the clear waters, that you must foul the rest with your feet? 19 As for My flock, they must eat what you tread down with your feet and drink what you foul with your feet!’”20 Therefore, thus says the Lord God to them, “Behold, I, even I, will judge between the fat sheep and the lean sheep.
21 Because you push with side and with shoulder, and thrust at all the [t]weak with your horns until you have scattered them abroad, 22 therefore, I will deliver My flock, and they will no longer be a prey; and I will judge between one sheep and another.
23 “Then I will set over them one shepherd, My servant David, and he will feed them; he will feed them himself and be their shepherd. 24 And I, the Lord, will be their God, and My servant David will be prince among them; I the Lord have spoken.”
Based on this passage, Jesus has placed Himself squarely in the context of this messianic portrait. God’s people, His flock, have been run astray by irresponsible shepherds, and Jesus will care for them and bring them back. God is called “the Shepherd of Israel” (Ps. 80:1; Ps. 23; Is. 40:10-11), and Jesus identifying Himself as “the Good Shepherd.” The heart of the gospel is concerned with the provision that God has made for the salvation of His sheep and this involves the death of the shepherd.
 Andreas J. Kostenberger, Encountering John. (Grand Rapids, MI: Baker Academic, 1999), 122.
 Leon Morris, Jesus is the Christ: Studies in the Theology of John. (Grand Rapids, MI: William B. Eerdmans Publishing Co., 1989), 114.
 Ibid, 115.
 Andreas J. Kostenberger, Encountering John. (Grand Rapids, MI: Baker Academic, 1999), 123.
 Leon Morris, Jesus is the Christ: Studies in the Theology of John. (Grand Rapids, MI: William B. Eerdmans Publishing Co., 1989), 117.