Forgive me if you have already answered this question. My friend and I are wondering about the "unforgivable" sin of blasphemy. Could you please comment on this? Thank you.
The Bible never speaks of an "unforgivable" sin, exactly. It does speak of sins that will not be forgiven, which may practically equate to the same thing. The passage in its full context is Matthew 12:22-37. The two sins that it says will not be forgiven are "blasphemy of the spirit" and "speaking against the Holy Spirit."
The word we transliterate blasphemy should probably be translated "injurious speech." In legal terms, it would be called slander. The Jews call it "lashon hara," or "evil speaking." In the scripture, particularly in the New Testament, it is almost always used in the sense of slandering God. In this context it means saying that God's word is really from Satan.
(You may quit reading here and have the basic answer. For details on the passage in Matthew, read on.)
In verse 31, the one mentioning blasphemy , most translators insert the words "against" and "Holy" to read "blasphemy against the Holy Spirit." This may have caused a lot of people to misunderstand the scripture. Taking out the words that aren't necessarily in the original, the verse reads "Wherefore I say unto you, All manner of sin and blasphemy shall be forgiven unto men: but the blasphemy of the spirit shall not be forgiven unto men." I think it is a significant difference.
Let us look at the whole context. Jesus had healed a man with a demon. Some had said (probably in their own thoughts and not out loud) that Jesus healed by the power of Satan. "Knowing their thoughts," Jesus responded with the line most often attributed to President Lincoln, "a house divided against itself can not stand." In other words, if Satan cast out demons he would be working against himself, which is not logical. Then he went into the discussion of sins that will not be forgiven. Finally, he says that we will be judged on the words we speak. He is not accusing his accusers of blasphemy; he is warning them that they are getting close to it.
All sin and blasphemy that man commits can be forgiven him. But if his spirit really believes there is no God, it will not be forgiven him. Of course, the only way we can know would be if he dies maintaining that there is no God. (In other words, anyone who is worried that they have committed this sin has probably not committed it.)
The next sentence is slightly different. In it, Jesus specifically says that anyone who speaks against the Holy Spirit (as opposed to speaking it only in his own spirit) will not be forgiven. By the definition of blasphemy above, speaking against the Holy Spirit would be blasphemy. But what is the difference between speaking against Jesus and against the Holy Spirit? Jesus, while on earth, calling himself the Son of Man, was open to question as to whether he was God. His deity was proven not so much by his miraculous works or his words before his death as by his resurrection. On the other hand, anyone who speaks against the Word of God, the Holy Spirit, denying He is God's word is liable to not being forgiven. Some modern scholars who deny the inspiration of the scriptures and a few people who vocally attack inspiration are the ones who should worry about this.
The two sentences taken together, then, seem to say that if one believes firmly in his heart, or openly says that the word of God is not inspired, he will not be forgiven in the world to come, because he will refuse to change his position in this world.
Thank you for an excellent question.