Maybe you should read Mark 13 again. For Christ Jesus does make mentioning of the blasphemy of the Holy Spirit. And when it will take place and who can commit it.
Look in Mark 13:11, Christ Jesus giving for warning his elect people, that when they are delivered up before the antichrist, Not to premeditated nor give any thought beforehand what they are to say, for it is not them that shall speak, but the Holy Spirit speaking thru them.
Now if the elect speaks, before the Holy Spirit speaks thru them, Then the elect just Blasphemy against the Holy Spirit.
Which will only happen during the tribulation and no other time.
Therefore in Mark 13:11 Christ Jesus has give what the Blasphemy of Holy Spirit is.
By not letting the Holy Spirit speak thru them first. But speaking before the Holy Spirit speaks thru them. This is Blasphemy against the Holy Spirit.
When does this take place, only during the tribulation.
By God's elect people, when they are delivered up before the antichrist.
Who in your opinion are Gods elect people? Christians in general or a particular group of them?