I got this question yesterday and although I have written this in a previous post it is worth repeating. What determines if a person is both called and then chosen? Because the Bible says many are called but few are chosen. The answer is a remarkably simple statement. In fact the answer is wrapped up in another question. Did you answer the call? Or did you find other things in your life more important. If you found nothing in your life more important than GOD's call then you are chosen.
Mark 8:35 "For whoever wishes to save his life will lose it, but whoever loses his life for My sake and the gospel's will save it.
Most of us are not chosen because we have far to many things going on in our worldly lives than to think about what Jesus wants us to do for HIM.