In John 3:14-15, Jesus says that His atonement is only effective for those who believe in Him.
No one is born Jesus's Sheep: When Jesus says, “I know My own and My own know Me,” He is referring to a mutual and intimate, interpersonal relationship. “The Lord knows who are His,” (2 Timothy 2:19) and “if anyone loves God, he is known by Him.” (1 Corinthians 8:3)
. Either this is something that we are born with, or it is something that we grow into. Since no one is born as a believer, it would stand to reason that being one of Christ’s sheep (or follower) is something that results from conversion rather than birth.
Later in that chapter, Jesus encouraged unbelievers to consider the evidencce of the miracles so that they would know the truth. (John 10:37-38) So, just because they are presently not His sheep, does not mean that they cannot
become His followers.
You cannot take John 10:15 in isolation. Just because Jesus died for His Sheep, does not mean He did not die for others. If you take Galatians 2:20 in isolation, you can argue that Jesus died only for Paul
Galatians 2:20 I have been crucified with Christ and I no longer live, but Christ lives in me. The life I now live in the body, I live by faith in the Son of God, who loved me and gave himself for me.
Jesus died for the entire world: 1 John 2:2 amd 1 Timothy 2:6 say that Jesus died for all men. But again just because Jesus died for all men, does not mean it is effective for all men.
1 John 2:2 And He Himself is the propitiation for our sins, and not for ours only but also for the whole world.
1 Timothy 2:1 I urge, then, first of all, that petitions, prayers, intercession and thanksgiving be made for all people— 2 for kings and all those in authority, that we may live peaceful and quiet lives in all godliness and holiness. 3 This is good, and pleases God our Savior, 4 who wants all people to be saved and to come to a knowledge of the truth. 5 For there is one God and one mediator between God and mankind, the man Christ Jesus, 6 who gave himself as a ransom for all people. This has now been witnessed to at the proper time.
If Jesus did not die for all people, why does Paul say that Jesus is the Savior of all people?
1 Timothy 4:10 That is why we labor and strive, because we have put our hope in the living God, who is the Savior of all people, and especially of those who believe.