I am the good shepherd. The good shepherd lays down his life for the sheep. He who is a hireling and not a shepherd, whose own the sheep are not, sees the wolf coming and leaves the sheep and flees; and the wolf snatches them and scatters them. He flees because he is a hireling and cares nothing for the sheep. I am the good shepherd; I know my own and my own know me, as the Father knows me and I know the Father; and I lay down my life for the sheep. And I have other sheep, that are not of this fold; I must bring them also, and they will heed my voice. So there shall be one flock, one shepherd. For this reason the Father loves me, because I lay down my life, that I may take it again. No one takes it from me, but I lay it down of my own accord. I have power to lay it down, and I have power to take it again; this charge I have received from my Father." John 10:11–18 (RSV)
'I am the good shepherd.' Jesus speaks with a clarity of purpose that unsettles those who hear Him. Those who listen with any measure of attention cannot deny what Jesus is claiming. 'I AM' on the lips of Jesus leaves no doubt that He and the Father are One.
Once you hear it, you cannot unhear it. Jesus is either the Son of the Living God as Peter confessed at Caesarea Philippi, or He is a madman who should be locked up for His safety. If He is a madman, the priests, scribes, and Pharisees would have let him be, babbling like a fool in the marketplace.
If He is God, if He is the One who spoke to Moses out of the burning bush, then one must bow before Him. Or at least one would think that would be the case. It is a wonder that instead of rejoicing that the Messiah has come, plots and schemes are hatched to undo Him.
The leaders of the Temple had their religion to protect. They had the means by which they could insert themselves in the lives of others and demand obedience. If you have a solid religion, you don't even need to believe; you have the power. A madman Jesus would play right into their hands. They could point to Him and say, 'See, He is insane, He cannot be the One! We will keep you safe from Him.'
'I am the good shepherd.' Jesus cares little for religion. He has come to set people free. He will lay down His life for them, and be raised from the dead for them. He does this so that they might belong to Him, and He will be their Shepherd. There will be one flock, responsive to His voice, in a living relationship that reflects the love of the Father for the Son.
He taught the woman at the well; the Messiah will lead us to worship in Spirit and Truth. Jesus, the Good Shepherd, leads us out into the Father's pasture, where we will worship along with all creation.