“Truly I tell you, people can be forgiven all their sins and every slander they utter, but whoever blasphemes against the Holy Spirit will never be forgiven; they are guilty of an eternal sin.”
The scope of God’s mercy is truly amazing. He is able to forgive any and every sin (even gross, deliberate and repeated sins). Under the Old Covenant, there were some sins not covered by the sacrifices: murder, adultery, idolatry, and any sin committed “defiantly” (Numbers15:30). But even these are dealt with by the death of Jesus (Acts 13:39).
There is just one exception to this rule: blasphemy against the Holy Spirit. Sometimes called the “unforgivable sin”, it has attained considerable notoriety – and caused no little confusion over what it actually means.
First of all, what is blasphemy? It’s more than ordinary insults or angry words; it’s a deliberate attempt to destroy God’s reputation through slander. Now people blaspheme against God and against Christ all the time, very often through blindness or ignorance. These sins are serious – but not unforgivable, as the case of Paul proves. “Even though I was once a blasphemer and a persecutor and a violent man, I was shown mercy because I acted in ignorance and unbelief.” (I Timothy 1:13)
So what is different about blasphemy against the Spirit? The Holy Spirit is God engaging with the world, the Person of the Trinity who works with unbelievers to convict them of sin (through their conscience), reveal Christ to them (through Scripture or the Church), and bring them to the point of repentance (see John 16:8-11). Those who set themselves against the Father or the Son are still open to the Spirit; but those who turn knowingly against the Spirit cut themselves off from the Father and the Son as well. The reason that Jesus warns the theological experts from the Jewish Sanhedrin so solemnly about the unforgivable sin is that they are in danger of committing it (note that He doesn’t actually say that they have committed it). They think that by attributing the Spirit’s work to Satan they can dismiss the claims of Jesus (Mark 3:22); but such deliberate and calculated defiance of God’s revelation is the essence of blasphemy against the Spirit.
So ‘blasphemy against the Spirit’ is a sin unlike all others.
It is NOT the same as ‘grieving the Spirit’ (Ephesians 4:30).
It is NOT a sin committed by a Christian who ‘should have known better’. David sinned like that when he committed adultery with Bathsheba and murdered her husband – but even he was forgiven (II Samuel 12:13)!
It is NOT the same as backsliding. Peter denied Jesus three times – but even he was forgiven (John 21:15-19)!
Someone who blasphemes against the Spirit has passed the point of no return. They have hardened their conscience irretrievably; they have no sense of sin and no fear of judgement. They cannot be forgiven because they cannot repent; they have put themselves forever outside the reach of God’s grace.
So all those people who worry about having committed the unforgivable sin cannot possibly have done so! The fact that they are concerned about it is proof that the route of repentance and forgiveness is still open to them. The very few people who should worry are the ones who do not care – the ones who are so determined to go to Hell that not even God can stop them…