Why is it that some respond positively to the voice of the Good Shepherd while others do not? The explanation that Jesus himself gives in John chapter 10 is that at the end of the day, his sheep are the ones who hear his voice, and that those who persist in unbelief are not among his sheep. What are the implications of this message on grace and free will? Are these new ideas or are they rooted in concepts taught throughout the Old Testament? Shane Rosenthal discusses these questions and more with Justin Holcomb, author of On the Grace of God.