Matthew 12:31-32,
Therefore I say to you, every sin and blasphemy will be forgiven men, but the blasphemy against the Spirit will not be forgiven men. Anyone who speaks a word against the Son of Man, it will be forgiven him; but whoever speaks against the Holy Spirit, it will not be forgiven him, either in this age or in the age to come"
This gets into what is the "blaspheme against the Holy Spirit?" I would say that it is dieing without asking for forgiveness of your sins. After you're dead, it's too late and therefore can't be forgiven. All sins can be forgiven, if we ask prior to death.
You and I may disagree slightly on this, and that's fine. I think we would both agree that God will be the final decider on that.
Sincerely