From: Luke 12:8-12
Various Teachings of Jesus (Continuation)
(Jesus said to His disciples,)  "And I tell you, every one who acknowledges Me before men, the Son of Man also will acknowledge before the angels of God;  but he who denies Me before men will be denied before the angels of God.  And every one who speaks a word againstthe Son of Man will be forgiven; but he who blasphemes against the Holy Spirit will not be forgiven.  And when they bring you before the synagogues and the rulers and the authorities, do not be anxious how or what you are to answer or what you are to say;  for the Holy Spirit will teach you in that very hour what you ought to say."
8-9. This follows logically from Christ's previous teaching: worse than physical evils, worse even than death, are evils of the soul, that is, sin. Those who out of fear of temporal suffering deny our Lord and are unfaithful to the demands of the faith will fall into a greater evil still: they will be denied by Christ Himself on the Day of Judgment; whereas those who are penalized in this life because of their faithfulness to Christ will receive the eternal reward of being recognized by Him and will come to share His glory.
10. Blasphemy against the Holy Spirit consists in maliciously attributing to the devil actions which have God as their origin. A person who does that prevents God's pardon from reaching him: that is why he cannot obtain forgiveness (cf. Matthew 12:31; Mark 3:28-30). Jesus understands and excuses the weakness of a person who makes a oral mistake, but He is not similarly indulgent to someone who shuts his eyes and his heart to the wonderful things the Spirit does; that was the way these Pharisees acted who accused Jesus of casting out demons in the name of Beelzebul; it is the way unbelieving people act who refuse to see in Christ's work a sign of the goodness of God, who reject the invitation God offers them and who thereby put themselves outside the reach of salvation (cf. Hebrews 6:4-6; 10:26-31). See the note on Mark 3:28-30.
[The note on Mark 3:28-30 states:
28-30. Jesus has just worked a miracle but the scribes refuse to recognize it "for they had said `He has an unclean spirit'" (verse 30). They do not want to admit that God is the author of the miracle. In this attitude lies the special gravity of blasphemy against the Holy Spirit--attributing to the prince of evil, to Satan, the good works performed by God Himself. Anyone acting in this way will become like the sick person who has so lost confidence in the doctor that he rejects him as if an enemy and regards as poison the medicine that can save his life. That is why our Lord says that he who blasphemes against the Holy Spirit will not forgiven: not because God cannot forgive all sins, but because that person, in his blindness towards God, rejects Jesus Christ, His teaching and His miracles, and despises the graces of the Holy Spirit as if they were designed to trap him (cf. "St. Pius V Catechism", II, 5, 19; St. Thomas Aquinas, "Summa Theologiae", II-II, q. 14, a. 3).]
Source: "The Navarre Bible: Text and Commentaries". Biblical text taken from the Revised Standard Version and New Vulgate. Commentaries made by members of the Faculty of Theology of the University of Navarre, Spain. Published by Four Courts Press, Kill Lane, Blackrock, Co. Dublin, Ireland.
Reprinted with permission from Four Courts Press and Scepter Publishers, the U.S. publisher.