The divine character of Jesus’ ministry was unmistakable. When He cast out demons, they never returned. Clearly, our Lord came in the authority and power of God Himself, for He decisively bound the strong man, Satan (Mark 3:22–27). To understand today’s passage, we must keep in mind this self-evidently divine characteristic of Jesus’ ministry.
Mark 3:28–30 includes one of Jesus’ most difficult sayings, His identification of an “eternal sin” that cannot be forgiven—blasphemy “against the Holy Spirit” (vv. 28–30). Although Jesus does not specifically define this sin, the context reveals this transgression as the persistent, knowing, verbal attribution of the work of God to Satan.
First, Mark’s comment “for they were saying” (v. 30) as he narrates Jesus’ response to the scribes shows that the blasphemy Jesus has in mind is a verbal sin. The scribes were sinning with words, with statements against our Savior. Moreover, the same comment from Mark means unforgivable blasphemy is a persistent sin. “Were saying” is in the progressive voice, which conveys ongoing action. The scribes spoke against Jesus not merely one time; rather, they were so hardened against Him that they continued to associate Him with Satan.
Such hardness is particularly noteworthy because it came from the resident biblical experts. So, we cannot understand what Jesus means by the blasphemy against the Holy Spirit unless we recognize the scriptural knowledge of our Lord’s opponents. Throughout His earthly ministry, Jesus held the religious leaders to a high standard. Christ expected them to know the Hebrew Scriptures, or Old Testament, so well that they could rightly identify God’s work (Matt. 23; John 3:1–15). So, the blasphemy of the Spirit does not arise from mere ignorance. When people know the Scriptures well and yet not only fail to recognize Jesus as Messiah but also openly reject Him, they are standing on perilous ground.
Blasphemy of the Spirit, then, is not the occasional bad thought or episode of anger against God. Such things are sins, to be sure, but they are not the persistent, deliberate rejection of the Lord’s work that shows itself in a willful attribution of God’s actions to Satan himself. Such blasphemy is unforgivable not because the Lord is unwilling to forgive but because a person guilty of such sin has fully and finally hardened his heart against the grace of God.