In regards to your first paragraph. You wrote,”our Lord has committed himself to keeping those who are his, revealing that no one is able to rip or take any of his sheep (children) away from him.” Actually, the verse says more than that. It says Christ promises those sheep that are His, “shall never perish”. You skipped those important three words. The part of the promise you quoted is focused on by some, who add, ‘but you can jump out of his hands’. So those would perish, since they left on their own, they were not forced to leave. Jesus did not leave that as an option, he said they would never perish.
In paragraphs 2 you wrote, “The sheep hear His voice…” That is not correct. It says, “My sheep hear my voice…”. Why does he call them “my” sheep? He later tells us “My Father which gave them me…” You refer to cooperation on the sheep’s part. I don’t see that word nor any word that implies the sheep decide something. You are presenting the view that the sheep hear, decide to follow the shepherd but can decide to leave the shepherd. This is not presented in the passage.
In paragraph 3 you wrote, “Christ conditioned the security of not being snatched away from him on the basis of the sheep (Christian), who both hear, and willfully follow him.” Again, you emphasize the snatching away part. If Jesus had just promised we would not be snatched away, then your presentation would be OK. But Jesus said we would never perish. I see nothing in these verses about the sheep deciding or willing something. What do those words “shall never perish” mean?
My sheep hear my voice. That is passive.
I know them, Christ knows who the Father has given him.
They follow me, why? verse 4 states the reason, “..his own sheep…follow him for they know him.” No mention is made of a ‘cooperative’ response. It sounds more like a stimulus response, also know as a knee-jerk response.
You are creating a third group of sheep. 1) other sheep, 2)my sheep who follow me, and 3)my sheep who do not follow me. Jesus gives only two groups.
1) Other sheep who are not his, who do not believe
2) My sheep, who are his, who follow him
It is this second group that Jesus makes this unconditional promise to in verse 27, “they shall never perish.”