I made a video last year, titled "Please don't reject the gospel." That would be the most relevant video I've done approaching the subject, without labeling it.
In Mathew 12, there's an account of Jesus saying, that all manner of sin and blasphemy will be forgiven unto men, but the blasphemy against the Holy Ghost shall not be forgiven unto men; neither in this world or in the world to come.
This is in response to the accusation the pharisees made against Him, accusing Him, basically, of working by the power of the devil.
Jesus could see into them, that they had rejected Him, and would never believe on Him. Their heart was irrevocably hardened against Jesus. Their fate was sealed with no hope of salvation remaining.
Some would say, it's not possible to blaspheme the Holy Spirit today, since Jesus isn't physically present. I think that it is possible, though. But, not being God, we're not able to look into someone and see that in them, that we could say that they've done that, and reached the point of no return.
We can say, that the one unforgivable sin is never having placed faith in Jesus alone for salvation, during a person's life. Of not accepting the finished work of Christ. Because faith in Christ alone, in His finished work, is the only way of salvation and forgiveness of all sin. If it's rejected during this life, there's no other way to be saved or have sins forgiven. There is no other sacrifice for sin.
I do think it's possible for someone to reach the point of no return in life, to have utterly rejected the truth of the gospel, to have rejected Christ to the point that their heart is so hardened that they'll never believe. I can't say when that is, but it's a warning for people to, at the very least, not reject the gospel.
It's a warning found in Hebrews 10. This shouldn't put any believer into fear, though. If someone has placed their faith in Jesus alone, they have been indwelt by the Holy Spirit, born again, and they are eternally secure. They have accepted the ministry of the Holy Spirit and believed on Jesus.
If the Holy Spirit comes to an unbeliever, testifying to the truth of Jesus, my strong advice would be, at the very least, remain open to it, even if you don't believe it. Don't reject it as a possibility. Please be reverent to the ministry of the Holy Spirit and don't insult the Holy Spirit, lest your wishes are finally granted, and God leaves you to it, to be fully given over to delusion.
In light of Hebrews 10:29, it's concerning when you see people not just questioning the gospel, but rejecting it and mocking and ridiculing it, railing against it. There are many very religious pharisee-like people that do this.
Hebrews 10 29 Of how much sorer punishment, suppose ye, shall he be thought worthy, who hath trodden under foot the Son of God, and hath counted the blood of the covenant, wherewith he was sanctified, an unholy thing, and hath done despite unto the Spirit of grace?
When you look at the Greek words used to describe these people in Hebrews 10:29, it's not describing somebody struggling to have assurance in Jesus, or questioning things. They are described as rejecting with disdain, the blood of Jesus as fully powerful and holy, able to forgive all sin and make one fully holy, all by itself. They insult it, and mock it.
It should be seen as a warning, but the really concerning thing, is that these people usually don't care at all, and seem completely given over to a deception.
However, if somebody will come to have faith in Jesus, in His finished work, during their life, that would indicate that they haven't committed the unforgivable sin; that they haven't blasphemed the Holy Spirit, since they were finally sensitive to the ministry of the Holy Spirit, testifying of Jesus and His finished work.
I think this has a real significance during The Tribulation. Since people refused to believe the truth, they'll be given over to a great delusion, and accept the antichrist. Their allegiance will be to the antichrist, and in so doing, they'll utterly reject Jesus. They'll take the mark of the beast, and their fate is sealed.
So the warning to people in The Tribulation, to those that can still hear and be sensitive to the truth of Jesus, is don't reject Jesus; don't reject the gospel, and don't take the mark of the beast. Even if you don't believe in Jesus, yet, at least remain open to it, and give yourself a chance. And the encouragement would be to put your faith in Jesus, in His finished work on the cross, and reject the antichrist, and don't take the mark of the beast.
I pray that these words will reach those who need to hear it.