Its a great question. Ever have a bad day and rattle out a few expletives with religious overtones? I'm pretty sure that isn't it!
I think we need to consider the meaning of the words Holy Spirit and Blaspheme.
Holy Spirit is used in vary contexts in both the OT and NT.
Most importantly how Jesus uses the word Holy Spirit that He links with being the comforter:
John 14:16-19
He then explains the role of the Holy Spirit:
John 14:26-28
I'm never entirely sure about the varying understandings Christians have of Holy Spirit or Paraclete
Paraclete - Wikipedia
How Baha'is see the Holy Spirit is more similar to the Return of Christ or the next Messiah.
Why that makes more sense than some internal spiritual experience is the former allows for God's progressive revelation in a very clear manner, whereas every Joe can claim to some special knowledge because they have the 'Holy Spirit' within them.
In the book of Acts where the words Holy Spirit is used more than any other NT book, it is more like the Spirit of Christ comes upon the apostles. That is they are so animated by the reality of Christ in their inner being that are empowered to spread the gospel far and wide. I think its a different use of the same word and why the Holy Spirit is seen as an internal spirit rather than a person in John 14.
Blaspheme has a variety of uses. For a Baha'i it is one who opposes the Returned Christ or His spirit. However there is a special emphasis on those who knowing misrepresent His Cause through slander and calumny thus causing confusion and antipathy in those who would seek the truth. We know Jesus forgave those who threw lots for His clothing. Paul who opposed and persecuted Christians was so transformed by His experience of Christ that he became one of greatest champions for the Cause. We can safely say Matthew 12:31-32 did not apply to either the Roman guards or the apostle Paul.
Bahá'í Reference Library - Some Answered Questions, Pages 127-128
