In John 10:28 there is a three-fold proclamation, for Jesus' sheep, of eternal security in the Lord:
And I give unto them 1) eternal life, and they 2) shall never perish, 3) neither shall any man pluck them out of my hand.
1) the life that is given is eternal or everlasting--that means it will last for ever.
2) the person who has eternal life will never perish--never is a very strong word, and I leave it to the reader to understand what it means that I, as one of God's sheep, will never perish.
3) no one will pluck me out of Jesus' hand. This is reinforced by John 10:29-30, My Father, which gave them me, is greater than all; and no man is able ot pluck them out of my Father's hand. I and my Father are one.
Here it is not only true that no one will pluck me out of Jesus' hand, it is also true that Jesus' hand is also the hand of the Omipotent Father, and no one is able to pluck me out of His hand.
To which the opponent of this sound doctrine of eternal security will say,
"Yes, but it is possible for one of Jesus' sheep to walk away from Him, and if they do so they are lost."
I reply that we ought to consider this as a possibility, but that in considering this possibility it ought to create in us the fear of the Lord.
And in Jeremiah 32:39-40 it is written, And I will give them one heart, and one way, 1) that they may fear me for ever, for the good of them, and of their children after them: And 2) I will make an everlasting covenant with them, 3) that I wil not turn away from them, to do them good; but I will 4) put my fear in their hearts, that they shall not depart from me.
Now compare #'s 1 and 4. God will give to the true believers one heart, and one way, so that they might fear the Lord for ever, and through that fear they shall not depart from Him. Therefore it is an eternal fear of the Lord by which the servants of the Lord will never volitionally leave the palm of His hand for ever.
#'s 2 and 3 also have a bearing on eternal security, but numbers 1 and 4 help us to understand something that we may not find in John 10:28-30, and that is that the true believer will never volitionally leave the service of God and being in the palm of HIs hand; and we know also from John 10:28-30 that no one can pluck the same person out of the Father's hand.
How then can one lose their salvation? No outside force can take us out of salvation; the fear of the Lord means that we will never leave; is it possible that God would simply thrust us out?
No; for it is written (John 6:37) that Jesus said, All that the Father giveth me shall come to me; and him that cometh to me I will in no wise cast out.