The sin Jesus speaks about here is termed “sin against the Holy Spirit”, because external expressions of God’s goodness are specially attributed to the third person of the Blessed Trinity. Sin against the Holy Spirit is said to be unforgivable not so much because of its gravity or malice but because of the subjective disposition of the sinner in this case: his attitude shuts the door on repentance. Sin against the Holy Spirit consists in maliciously attributing to the devil the miracles and signs wrought by Christ. Thus, the very nature of this sin blocks the person’s route to Christ, who is the only one who can take away the sin of the world (Jn 1:29), and the sinner puts himself outside the range of God’s forgiveness. In this sense the sins against the Holy Spirit cannot be forgiven.