There’s no if in regards to the sheep that Jesus is responsible for.
My sheep hear My voice, and I know them, and they follow Me; and I give eternal life to them, and they will never perish; and no one will snatch them out of My hand. My Father, who has given them to Me, is greater than all; and no one is able to snatch them out of the Father’s hand.
— John 10:27-29
1. “My sheep” is an metaphor used in the first century to indicate “one who follows me.” Sheep were followers.
2. This is Jesus’ way of simply saying, “You do not believe because you are not following Me, just as you were not following my Father before Me.” If they
had been followers of the Father, He would have gladly given and drawn them to His Son. The objectors were not right with God, and Jesus was calling attention to that fact, in order to truly help them, which is because Jesus really does love His enemies. Jesus came to save the condemned, not to condemn those who are already condemned.
3. It’s certainly not the same as saying, “You do not believe because you weren’t elected from before the foundation of the world.”
4. While it’s true that they were not of God and were not of Christ’s sheep, what did Jesus tell them? He said of those who were “not of My sheep” to consider the evidence of the miracles so that they can become one of His sheep: “‘If I do not do the works of My Father, do not believe Me; but if I do them,
though you do not believe Me,
believe the works, so that you may know and understand that the Father is in Me, and I in the Father.’” (John 10:37-38) So people who do not believe in Jesus and who are declared by Him to not be one of His sheep (followers), still can be. Their predicament was not fixed and unchangeable.
We understand that these people being rebuked by Christ are “goats” principally
because of their refusal to listen and learn from the Father, rather than for something with which they had absolutely no control over (i.e. Total Inability from Birth). Those who did willingly listen and learn from the Father would desire to follow the Son as well (be His sheep), which is why they believe the Son. So if it helps, just exchange the word “sheep” with the word “follower” at John 10:25-27 and the result is that Jesus’ intent becomes quite clear.