A chosen people?

I am currently reading through Acts, when i came across something that puzzled me in verse 13:48. Paul and Barnabas are traveling around telling people about Jesus' death and resurrection when they come to Antioch.

47. For this is what the Lord has commanded us:

"I have made you a light for the Gentiles,
That you may bring salvation to the ends of the earth."

48. When the Gentiles heard this, they were glad and honored the word of the Lord; and all who were appointed for eternal life believed.

Now that last little bit is what puzzles me. Doesn't everyone have the chance to believe in God? Are there certain individuals out there who God specifically closes there eyes so that they won't believe? I know that God is all knowing and knows how a person dies and where they go (book of life) So is that sorta what Paul is writing here? That the people who won't believe anyways aren't allowed to believe? Personally this kind of scares me, are there people out there that it's not that they won't turn to God... but that they can't?