Here is the story from the Bible scholar Sir George Adam Smith that so well illustrates what Jesus meant by His astonishing statement, I am the door of the sheep (v. 7 & 9).
He was one day traveling in Palestine with a guide, and came across a shepherd and his sheep. He fell into conversation with him. The man showed him the fold into which the sheep were led at night. It consisted of four walls, with a way in. Sir George said to him, “That is where they go at night?” “Yes,” said the shepherd, “and when they are in there they are perfectly safe.” “But there is no door,” said Sir George. “I am the door,” said the shepherd. He was not a Christian so he was not speaking the language of the New Testament. Rather, he was speaking from a Mid-Eastern shepherd’s point-of-view. Sir George looked at him and said, “What do you mean you are the door?” Said the shepherd, “When the light has gone, and all the sheep are inside, I lie in that open place, and no sheep ever goes out but across my body, and no wolf comes in unless he crosses my body; I am the door.”
Because Jesus is the door of the sheep, we should believe in Him as the Messiah and follow Him as opposed to false and harmful impostors. There are two implications that result. As the door Jesus alone dictates legitimate access to the sheep (7-8) and Jesus alone enables maximum benefit for the sheep (9-10) – salvation, security, sustenance, and satisfaction. This is the abundant life Jesus came to give!