While it is true that you can never really go so far from God that He refused to forgive (maybe with the exception of what's written in Luke 12:10), it is also true that you can close yourself off so much to the things of God that you aren't able to hear His voice anymore.  That seems to have been the issue with the Israelites.  They didn't want to listen to the voices of the prophets, and they were so certain that the path they were on would be sufficient for them.  Sadly, nothing could have been further from the truth.  In their sin, in their rebellion, in their unwillingness to listen – they were forced into exile.  Don't close yourself off from the Word of God.  Don't dismiss the promptings of the Holy Spirit.  God will still be willing to forgive, but it's possible to go so far from Him that your desire for forgiveness disappears.