As I've already explained, but you refuse to hear, is I agree no one can snatch His sheep from His hand—if indeed they're His sheep. However, a person can willingly turn their back on the Lord and forfeit any benefit they may have had previously. This is the only way a person can lose their salvation.
You quote verses like John 10:28 because it supports what you want to believe. But you you ignore the rest of scripture at your own peril. You've been fed false doctrine so long you can't comprehend that it can be any other way.
You quote verses like John 10:28 because it supports what you want to believe. But you you ignore the rest of scripture at your own peril. You've been fed false doctrine so long you can't comprehend that it can be any other way.
John 10:28 does not in any way support the doctrine of "eternal security". It says that the sheep (them) are given eternal life and they will never perish. The promise is clearly to the sheep. It is not a promise to those who are not sheep.
If you are not a sheep, you do not have eternal life and you will perish. Who is a sheep? The previous verse (27) says: "My sheep hear my voice, and I know them, and they follow me: " Sheep are those who are hearing Jesus' voice and are following Him. If you are not hearing His voice and following Him you are not a sheep and the promise of verse 28 does not apply to you.
The verse does not talk about the possibility or even the "how" of becoming a sheep or of no longer being a sheep.
The verse is a powerful promise and blessing to all who are sheep: to those hearing his voice and following Him.