“But you do not believe because you are not of my sheep. My sheep hear my voice, and I know them and they follow me. And I give to them eternal life, and they will never perish, and no one will be able to snatch them from my hand.”
Jesus then makes clear the position. What they needed to do was to forget their preconceptions and acknowledge Him as He was, and fall into line with His words. But He brings out that this they would not do because they were not of His sheep. They would not follow Him because they had not been given to Him by the Father (John 10:29; John 6:37; John 6:39). Of course the option was still open, but Jesus knew that they would only respond if they were one of His sheep, drawn by the voice of the Shepherd (John 10:4) and by the Father (John 6:44).
Those who were destined to be His would be revealed by their response and by their actions. They had an ear to hear. They had a will to obey. As His sheep they would be known to Him personally, and they would receive eternal life and listen to Him and obey Him. They would not fit Him into their own pattern, but would submit themselves to His will and purpose. And their reward would be that Jesus would give them eternal life and full certainty and security.
It is significant that right from the beginning Jesus makes clear that those who will be saved are the few (compare Matthew 7:13-14), those who follow Him. God's interest was not in numbers but in quality. Glorying in numbers is a sign of ‘popular religion'.
But two dangers always face sheep. One is that they will wander off and become lost, and perish of starvation and cold, or at the hands of wild animals. The other is that, while the shepherd is not watching, wolves will snatch them away and devour them. But neither would be possible for His sheep, for He would keep them and watch over them constantly, and if necessary seek them until He found them (Luke 15:4). They would be totally secure in His hands.
It is interesting that Jesus likened His people to sheep. Sheep are helpless creatures, rarely aggressive apart from the rams, and unable to cope on their own. Thus does Jesus demonstrate the total dependence of His own on Himself as the shepherd. They are to be trustful and quiet, like sheep, while not failing in their responsibility to follow Him, even, if necessary, to a cross (Mark 8:34; Matthew 16:24).