As a human I should imagine we can all think of people throughout history and even today who shouldn't have an eternity in heaven but we do not know the mind of God, only his nature which is that he loves us all and he desires all of us to come into the knowledge of his amazing saving grace,
There are a few verses in the bible that mention blaspheming against the Holy Spirit as being an unforgivable sin.
"And anyone who speaks a word against the Son of Man, it will be forgiven him;
but to him who blasphemes against the Holy Spirit, it will not be forgiven" (Luke 12:10)
As I understand it this verse refers to those who refuse Christ having heard the gospel, being convicted of their sin and the need to repent but refuse to do so, a deliberate act, in arrogance and rebellion.
We read that Paul was a blasphemer but was forgiven as he did it out of ignorance, as soon as he understood the grace of God and the love of Jesus he repented and was forgiven.
1 Timothy 1:13-15 “Although I [Paul]
was formerly a blasphemer, a persecutor, and an insolent man; but
I obtained mercy because I did it ignorantly in unbelief. And the grace of our Lord was exceedingly abundant, with faith and love which are in Christ Jesus. This is a faithful saying and worthy of all acceptance, that Christ Jesus came into the world to save sinners, of whom I am chief."
There are a number of schools of thought on it though.
What about you?