Jesus ensures that His Sheep shall believe in Him !
John 10:16
16And other sheep I have, which are not of this fold: them also I must bring,
and they shall hear my voice; and there shall be one fold, and one shepherd.
Whenever the Divine Being says that something shall or will happen, its a sure thing, and its sure because His Divine Power is engaged to perform it, as with Isaac, who was a child of promise. God said
Gen 17:19
And God said, Sarah thy wife
shall bear thee a son indeed; and thou shalt call his name Isaac: and I will establish my covenant with him for an everlasting covenant, and with his seed after him.
When the Son Issac was born it is written
Gen 21:1-2
1And the LORD visited Sarah as he had said,
and the LORD did unto Sarah as he had spoken.
2For Sarah conceived, and bare Abraham a son in his old age, at the set time of which God had spoken to him.
So it is with any Divine Promise, and so here Jesus promises that His Sheep shall hear His voice. He has all power both in Heaven and Earth to make good the promise
Matt 28:18
And Jesus came and spake unto them, saying,
All power is given unto me in heaven and in earth.
Now His Sheep are those He lay down His Life for as stated in
Jn 10:11,
15
11I am the good shepherd:
the good shepherd giveth his life for the sheep.
15As the Father knoweth me, even so know I the Father:
and I lay down my life for the sheep.
And it to these only is it promised that they shall hear His voice. To hear His voice in this respect means to believe on Him, thats the purport of
Jn 10:16
16And other sheep I have, which are not of this fold: them also I must bring, and
they shall hear my voice; and there shall be one fold, and one shepherd.
The hearing of His voice means that they shall live
Jn 5:25
25Verily, verily, I say unto you, The hour is coming, and now is, when
the dead shall hear the voice of the Son of God: and they that hear shall live.
They are the ones that liveth and believeth on Him
Jn 11:26
And whosoever liveth and believeth in me shall never die. Believest thou this?
This is so , and those who do not never believe, Jesus says there is a reason for that, which is this
Jn 10:26
26But
ye believe not, because ye are not of my sheep, as I said unto you.
Simply stated, Jesus is saying if ye were of the Sheep that I lay down my Life for
Jn 10:15, then shall ye believe, but since you are not, ye will not believe ! In fact, in another place it is revealed that they cannot believe
Jn 12:39
Therefore
they could not believe, because that Esaias said again,
The difference therefore between those who are believers, and those who cannot or will not believe is the Death of Christ, He died for His Sheep, and ensured that they Shall hear His voice, which means they shall live and believe on Him..