Some Christians believe and teach that the penalty for unbelief is hell fire.
Given that the Holy Spirit teaches us, through Scripture, that there is only one sin, and one sin only, which is totally unforgivable and results in the "eternal condemnation" of Gehenna (hell fire), i.e. blasphemy against the Holy Spirit - this should raise a question in our minds, viz:
Is unbelief the unforgivable sin?
Not every Christian is aware that all the apostles refused to believe the gospel of the risen Lord. Thomas usually gets singled out, but he was not alone in this.
When Mary Magdalene reported her eye witness account of the risen Lord to the apostles, Scripture says:
"And when they heard that He was alive and had been seen by her, they did not believe." (Mark 16:11)
When confronted with the joint eye witness accounts of not just Mary Magdalene, but also Joanna, Mary the mother of James, and the other women with them, what was the reaction of the apostles? Scripture says:
"And their words seemed to them like idle tales, and they did not believe them." (Luke 24:11)
After these events, Cleopas and another disciple talked to the risen Lord on the road to Emmaus, and even ate with Him. They immediately returned to Jerusalem to report their eye witness accounts to the apostles, but Scripture says:
"And they went and told it to the rest, but they did not believe them either." (Mark 16:13)
Now ask yourself: Was the unbelief of the apostles the unforgivable sin?
Apparently not. Jesus had mercy on their unbelief and later appeared to them in person.
Even so, when He did appear to them, Scripture records "they were terrified and frightened, and supposed they had seen a spirit. And He said to them, 'Why are you troubled? And why do doubts arise in your hearts? Behold My hands and My feet, that it is I Myself. Handle Me and see, for a spirit does not have flesh and bones as you see I have.' When He had said this, He showed them His hands and His feet. But while they still did not believe for joy, and marveled, He said to them, 'Have you any food here?' So they gave Him a piece of a broiled fish and some honeycomb. And He took it and ate in their presence." (Luke 24:37-43)
Only when confronted face to face by the risen Lord, and only after some gentle persuasion, only then did the apostles move from a position of unbelief to belief.
He reprimanded them, yes, but He did not condemn them to Gehenna. Scripture says:
"He rebuked their unbelief and hardness of heart, because they did not believe those who had seen Him after He had risen." (Mark 16:14)
As we all know, Thomas was not present when Jesus appeared to the other apostles. We are all very familiar with the reaction of Thomas to the combined eye witness accounts of the others:
"The other disciples therefore said to him, 'We have seen the Lord.' So he said to them, 'Unless I see in His hands the print of the nails, and put my finger into the print of the nails, and put my hand into His side, I will not believe'." (John 20:25)
When Thomas rejected the gospel of the risen Messiah, with the words "I will not believe", did his fellow apostles accuse him of the unforgivable sin? Hardly, for they had been guilty of the same unbelief.
Did our Lord give up on Thomas? Or did our Lord subsequently find another way - a face to face encounter - and have mercy on him?
When Thomas was subsequently face to face with the risen Lord Jesus Christ, did Jesus condemn him with the words "since you rejected the gospel given to you by my apostles, you have committed the unforgivable sin and I condemn you to eternal condemnation"?
Or did our Lord forgive his former unbelief and have mercy on him?
Jesus said to Thomas, "Reach your finger here, and look at My hands; and reach your hand here, and put it into My side. Do not be unbelieving, but believing." (John 20:27)
As with the other apostles, only when confronted face to face with the risen Lord, and only after some gentle persuasion, only then did Thomas become a believer.
Jesus said to him, "Thomas, because you have seen Me, you have believed. Blessed are those who have not seen and yet have believed." (John 20:29)
From these accounts, I believe that the apostles did not intentionally, wilfully, and obstinately, refuse to believe the gospel of the risen Lord. Therefore, I believe they did not blaspheme the Holy Spirit.
Consider, too, the example of Paul. Paul says:
"And I thank Christ Jesus our Lord who has enabled me, because He counted me faithful, putting me into the ministry, although I 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. However, for this reason I obtained mercy, that in me first Jesus Christ might show all longsuffering, as a pattern to those who are going to believe on Him for everlasting life." (1 Tim. 1:12-16)
Likewise, today, I observe that there are people who are "ignorantly in unbelief" but they may not necessarily intentionally, wilfully, and obstinately, refuse to believe the gospel of the risen Lord. Like the apostles, they may not have accepted the gospel when conveyed by word of mouth, but I do not believe they have blasphemed the Holy Spirit.
In my opinion, being "ignorantly in unbelief" and choosing not to believe the gospel when conveyed by a third party, either in writing (the Scriptures) or by word of mouth (an evangelist), is not the same as looking into the loving face of the risen Lord Jesus and saying - "I intentionally, wilfully, and obstinately refuse to believe in you."
Given that the Holy Spirit teaches us, through Scripture, that there is only one sin, and one sin only, which is totally unforgivable and results in the "eternal condemnation" of Gehenna (hell fire), i.e. blasphemy against the Holy Spirit - then I conclude that the penalty for unbelief is not eternal condemnation in hell fire.
