What constitutes blasphemy against the Holy Spirit is definitive in scripture.
Jesus did all His works through the Dunamis power of the Holy Spirit Acts 10:38.
When He cast out a demon via the power of the HS, the Pharisees said He did it using the power of Satan, instead.
Then Jesus said blasphemy against God and Himself is forgivable, but not blasphemy against the HS.
Thus it would seem obvious that blasphemy of the HS, is claiming that a work done by the power of the HS is a work done by the power of Satan.
No it is not obvious in the least. Scripture itself defines what constitutes the blasphemy.
Mark 3:
29 But he that shall blaspheme against the Holy Ghost hath never forgiveness, but is in danger of eternal damnation.
30 Because they said, He hath an unclean spirit.
Because they said JESUS had an unclean spirit.
Luke 11: 15 But some of them said, He casteth out devils through Beelzebub the chief of the devils.
Because they said JESUS casted out a demon by beelzebub.
Matt. 12:
23 And all the people were amazed, and said, Is not this the son of David?
24 But when the Pharisees heard it, they said, This fellow doth not cast out devils, but by Beelzebub the prince of the devils.
This one requires a little more explanation to understand. The Pharisees had taught for a long time that only messiah WHEN he COMES COULD DO THREE PARTICULAR MIRACLES (CALLED MESSIANIC MIRACLES)
1. Healing of a man born blind- John 9
2. Healing Jewish Lepers- Mark 1:40 (Jesus then gave authority for the disciples to heal lepers)
3. Casting out of a demon from one deaf and dumb Matt. 12.
When Jesus cast out the demon, He had done all three of the Messianic Miracles- so that the people turned to the Pharisess and rhetorically asked if Jesus was the Messiah (Son of David) They expected a yes because they had been taught only Messiah could do all three. Instead they accuse jesus of being demon possessed.
this is when Jesus revokes the offer of the kingdom to that generation of Israel , issues Judgment against the nation and then His ministry focused more on training the apostles for the church and hiding the truth from Israel by public teahing in parables (Matt. 13:
10 And the disciples came, and said unto him, Why speakest thou unto them in parables?
11 He answered and said unto them, Because it is given unto you to know the mysteries of the kingdom of heaven, but to them it is not given.
12 For whosoever hath, to him shall be given, and he shall have more abundance: but whosoever hath not, from him shall be taken away even that he hath.
13 Therefore speak I to them in parables: because they seeing see not; and hearing they hear not, neither do they understand.
14 And in them is fulfilled the prophecy of Esaias, which saith, By hearing ye shall hear, and shall not understand; and seeing ye shall see, and shall not perceive:
15 For this people's heart is waxed gross, and their ears are dull of hearing, and their eyes they have closed; lest at any time they should see with their eyes and hear with their ears, and should understand with their heart, and should be converted, and I should heal them.
What most people do not learn is what caused Jesus to change His ministry and why. The answer is the blasphemy of the spirit! That can only be done when Jesus walked on earth! The bible clearly defines it as Jesus performing miracles by being possessed.
YOu will not find any verse about the blasphemy apart from the Pharisees accusing Jesus Himself as demon possessed and reffering to believers being possessed if they perform a miracle.