One of the most challenging concepts in Scripture is that of the so-called "unforgivable sin," which is discussed in passages such as Matthew 12:22-37, Mark 3:20-30, and Luke 12:1-12. These passages appear to make a distinction between blasphemy against Jesus and blasphemy against the Holy Spirit. However, this raises an intriguing question: if God the Father, God the Son and God the Holy Spirit are one God, why is blaspheming against God the Son forgivable while blaspheming against God the Holy Spirit is unforgivable?
Before I answer this question, I should note that because of the extreme difficulty of the passages dealing with this topic, the church has developed a number of different interpretations for what Jesus means to imply here. For simplicity, I will not attempt to address all of these different interpretations. Instead, I will stick with the interpretation adopted in the GotQuestions article
"What is the unpardonable sin / unforgivable sin?"
I should also point out that there is no such thing as an unforgivable sin in Scripture, i.e., a sin which God
cannot forgive. The terms "unforgivable" and "unpardonable" are never actually used in Scripture. To my knowledge they only appear in the section headings of English translations like the New American Standard Bible, and are not a part of the original texts. In my opinion, this has led to a lot of unnecessary confusion about what the sin actually is. The sin is not something which God
cannot forgive. Rather, as Jesus Himself says, the sin "
shall not be forgiven" for the person who commits it. It is not a sin which God
cannot forgive, but which He chooses not to forgive.
Having clarified the nature of the sin we are discussing (which I will hereafter refer to as the "eternal sin" after Mark 3:29, NASB, let me actually answer the question I introduced earlier. Of the three passages I mentioned above, the first two show Jesus addressing the Pharisees and implicitly accusing them of the eternal sin. The third text mentions blasphemy against the Holy Spirit in the context of confessing or denying Christ on pain of persecution by unbelievers. God the Father is not mentioned in any of these texts, so we cannot speculate about any unique role which He plays in the context of the eternal sin.
Additionally, it is apparent from these texts that, whatever the eternal sin actually
is, it cannot be committed against Jesus (i.e., the Son of Man), since words or blasphemies spoken against Him may be forgiven; the eternal sin can only be committed against the Holy Spirit.
Why is this? Here is the best answer I have found: the passages seem to make a distinction between rejecting Christ out of
ignorance and rejecting Him
intentionally. For example, the apostle Paul said of himself that "I was formerly a blasphemer and a persecutor and a violent aggressor. Yet I was shown mercy because I acted ignorantly in unbelief" (1 Timothy 1:13, NASB). Clearly, Paul's blasphemies were forgiven because they were based, to a degree, in ignorant unbelief. The Pharisees, by contrast, could not claim this. Having just watched Jesus perform an incredible act of healing by freeing a man from demon possession, they should have responded by falling at Jesus' feet and worshipping, but instead, they attributed His miracle to the work of the devil. Their sin was not in ignorance, for they saw clearly that Jesus was the Messiah He claimed to be,
and chose to oppose Him anyway. This is the kind of hardness of heart which God refuses to forgive, but instead gives those who commit it over to the hardness of their hearts, allowing them to become cemented in their conscious rebellion against Him.
So, to state the answer a bit more clearly, the kind of blasphemy which God forgives is directed toward Christ and is based out of ignorance, but the kind of blasphemy which God does
not forgive is directed toward the Holy Spirit and is based out of conscious, intentional rebellion. It is understandable why God should be willing to forgive ignorant blasphemy but unwilling to forgive conscious blasphemy. What is difficult to understand is why these should be identified with blasphemy committed against, respectively, the Son of Man or the Holy Spirit.
I believe that we can understand this in the following way. Many people in our world hear about Christ and know about Christ without actually
knowing Him. Consequently, many may say blasphemous things about Him without truly knowing what they are saying — they are speaking in ignorance. This is why words spoken against the Son of Man (Christ) may be forgiven. On the other hand, in order to speak against the Holy Spirit, a person must already have received special, direct knowledge of the person and work of the Holy Spirit. In other words, the Holy Spirit must already have begun the work of conviction in that person's heart. In this way, when unbelievers choose to speak
against the Holy Spirit, they are no longer speaking ignorantly; they are consciously rejecting the work of the Holy Spirit in their lives, choosing instead to align themselves in opposition to His work, and not merely rejecting His work in their own lives, but speaking against Him in order to dissuade others from receiving His work in their hearts and lives as well.
Here is an analogy. Suppose that my daughter crafted a piece of art for me without my knowledge. On her way home, it fell out of her backpack and onto the sidewalk. While out for a walk that night, I stumbled upon it. Not knowing what it is or who it was for, I carried it to a trash can and tossed it inside. This would certainly be
bad, but it would also be forgivable; I didn't really know
what the piece of art was or who it was for, so it's understandable that I might simply throw it away.
By contrast, imagine that my daughter herself brings the piece of art to me and, after looking at it for a few moments, I immediately take it into the kitchen and put it in the trash. As before, the piece of art ended up in the trash. But now, there is something truly awful about what I have done; I have probably devastated my daughter in treating her creation and gift to me as utterly worthless. I have no longer merely thrown away the gift in ignorance; I have discarded it consciously and with evil intent.
This is much like the difference between blaspheming against the Son and blaspheming against the Spirit. Because the Son was in the world, He is like God's gift to us which some of us, in ignorance, may choose to reject. But the Spirit who is now in the world — convicting "the world concerning sin and righteousness and judgment" (John 16:8, NASB) — to consciously reject
His work and instead align oneself in opposition to Him is a truly fearsome and terrible sin. The fact that it is an
eternal sin indicates that it has eternal consequences.
So then, why does the topic of eternal sin arise in Luke 12? It is not obvious, at first glance, since Jesus does not appear to be responding to the Pharisees as He was in Matthew 12 and Mark 3. The connection appears to be this: in listening to Jesus speak (in verses 8-9) about His followers confessing Him before men, some might have been concerned that there would be no forgiveness for those who had denied Christ — in other words, would it be possible for someone who had denied Christ to repent and receive forgiveness? Jesus' answer appears to be "yes," since He takes this opportunity to emphasize that only blaspheming against the Holy Spirit is an eternal sin; blaspheming against the Son (say, for fear of one's life, and not out of conscious rebellion) was still an offense which might be forgiven. Indeed,
all of us were blasphemers against Christ before we were saved; if that offense is not forgivable, then no one can be saved. And finally, Jesus instructed His disciples not to be afraid, because the Holy Spirit Himself would
give them the strength to confess Christ when the moment came. So the caution against eternal sin fits in nicely with the context of Luke 12, although Jesus is not (in this case) leveling the charge against anyone in particular.
Understanding the notion of the "unforgivable sin" in this way should offer us a great sense of freedom and relief. I have personally encountered brothers and sisters in Christ who have wrestled with whether they themselves have committed such an "unforgivable" sin. The good news here is that we should not think of this sin as an obstacle to God's forgiveness, as if God's desire to cleanse us of sin would be prevented by our having sinned badly enough. There is
no sin which God is unable to forgive, and the eternal sin is the only one which God
chooses not to forgive. And of course, this can only be consistent with verses like Psalm 51:17 — "A broken and a contrite heart, O God, You will not despise" (NASB) — if the one who commits the eternal sin becomes incapable of a broken or contrite heart. Thus, a person who is broken and repentant over their sin has very likely not committed the eternal sin at all.
In short, there is no such thing as an unforgivable sin. God will never reject the heart which is broken and contrite over its sin. And that is very good news.