The book of John's primary intention was evangelistic. John states his main purpose clearly as “These are written that you may believe that Jesus is the Christ, the Son of God, and that by believing you may have life in his name.”
In John 10 Jesus is using the analogy of comparing himself to the Good Shepherd and his believers as the sheep. In the Old Testament the concept of “shepherd” symbolized a royal caretaker of God’s people. In the first illustration Jesus refers to those who enter the sheepfold other than through the gate as a thief or robber. But the one who enters through the gate is the shepherd of the sheep. The sheep recognize his voice and come to him and follow him because they know his voice. In the second illustration, because those who heard him did not understand, He explained to them that He was the gate for the sheep. All who came before Him were thieves and robbers. But the true sheep did not listen to them. He explains that He is the good shepherd, he knows his own sheep and they know him, just as his Father knows him and He knows the Father. He will sacrifice his life for them voluntarily because this is what his Father commanded. To me these passages provide the assurance that Jesus knows me just as his Father knows him, and if I know him, he will provide me with a “rich and satisfying life”. The more I spend time with Him, the more I am able to hear his voice. He has sacrificed his life for me so I can have a relationship that provides everlasting peace and love and fellowship for all eternity.
In the second part of the chapter Jesus claims to be the Son of God, but the people did not believe him because they were not his sheep. Jesus used his evidence of good works and miracles, and the fact that God set him apart and sent him into the world to carry out his work. The evidence of the miraculous works shows that "the Father is in him and He is in the Father." To me this just reinforces the fact that God sent Jesus into the world to take away the barriers to my having eternal life as long as I believe, and that God loves me, has a plan for me, and that plan is for good!
May we all spend time with Him so we can hear his voice!