Is unbelief sin?

“And when He has come, He will convict the world of sin, and of righteousness, and of judgment: ⁹ of sin, because they do not believe in Me; ¹⁰ of righteousness, because I go to My Father and you see Me no more; ¹¹ of judgment, because the ruler of this world is judged.” John 16:8-11

Some believe this “sin” is specifically unbelief in Christ. The Holy Spirit convicts of this “sin.” That view might be a problem for those who believe the death of Christ released everyone from their sins, because what about the “sin” of unbelief? (They say that people go to hell because of being unregenerate, not to “pay” for their sins—which Christ already paid for.) I've seen some say unbelief is a condition and not a sin, because unbelief keeps them from being saved. Unbelief does keep one in an unsaved state: see John 3:18 below.

Others may see it as sin in general: the Holy Spirit convicts people of sin in general, so that they will see their need for Christ. Jesus said, “²⁴ Therefore I said to you that you will die in your sins; for if you do not believe that I am He, you will die in your sins." John 8:24 One needs to believe in Jesus so that they don't die in their sins, but one must believe they are a sinner or else why do they need to believe?

I could see both views as possible.

Interestingly, about the time of my salvation, when I believe it happened, I was particularly convicted of my lack of trusting in Christ for may salvation—I was trying to reform myself.

But whether unbelief is a sin is a difficult question with respect to many things that can be believed or not believed. And what about persuasion?

Belief requires knowledge and persuasion. If one does not know, how can they be charged with sin? And even if one knows, can they believe, if they are not persuaded?

But there is a role that the will can play, if the evidence is undeniable.

But there are a lot of things people differ on, and to believe one thing and not another is not necessarily sin. To believe in a young earth or old earth is not a sin issue. To believe in pretrib or posttrib is not a sin issue. Some may say these are sin issues, but I don't believe so.

However, when it comes to salvation, unbelief does leave one in a condemned state.

¹⁸ "He who believes in Him is not condemned; but he who does not believe is condemned already, because he has not believed in the name of the only begotten Son of God. John 3:18

And there is the issue about the works of Jesus being denied, which because of the circumstances, to not believe he was the Christ would seem to be a sin—because the works were undeniable. And in connection with this is the “unpardonable sin,” which appears to be denying the undeniable working of the Holy Spirit: “²⁸ "Assuredly, I say to you, all sins will be forgiven the sons of men, and whatever blasphemies they may utter; ²⁹ but he who blasphemes against the Holy Spirit never has forgiveness, but is subject to eternal condemnation" Mark 3:28-29

That blaspheme must include unbelief because it involved attributing the working of God through Jesus to Satan. That the works of Jesus were clearly from God, and to attribute it to Satan is a sin that can't be forgiven. That attribution was due to unbelief, and since that unbelief can't be forgiven reveals that it is a sin. So there is unbelief that is sin. But not all unbelief falls into a sin category, due to what is at issue, as in things involving eschatology (prophecy) or ecclesiology (Church operation).