In Matthew 12:31, Yeshua states that blaspheme against the Holy Spirit will not be forgiven. For quite some time now, people have been claiming to have heard from the Holy Spirit various things. Or claim that the Holy Spirit has done various things. How do these people know it was the Holy Spirit? They don't! Because they don't know how to test the spirits. Those who do know how to test the spirits will easily be able to find everything wrong with what the "Holy Spirit" is saying or doing, and prove that it's not actually the Holy Spirit saying or doing these things. But what happens when these counterfeit spirits are exposed for what they really are? Those who claim to have heard from the Holy Spirit invoke Matthew 12:31, and even 1 Thessalonians 5:19. In other words, they will claim that you are blaspheming or quenching the Holy Spirit.
As with any doctrine that cannot withstand Biblical scrutiny, the wolves claiming that the Holy Spirit is speaking to them do not tolerate you testing the spirit to see if it's from Yahweh. Instead, they claim that you have committed the unforgivable sin of blaspheming the Holy Spirit, or that you are quenching the Holy Spirit in order to silence those who know better, and to cause impressionable people to believe that whoever opposes them are in the wrong. Of course, if any spirit claims to be the Holy Spirit but is not, then that spirit must be quenched and exposed for the fraud that it really is. For no spirit that is from Yahweh will falsely claim to be the Holy Spirit.
Testing to see if a spirit is actually the Holy Spirit requires knowledge and a robust understanding of the Bible. Especially of the Law of Yahweh, the Prophets, and the teachings of Yeshua. A good understanding of what the Holy Spirit has done historically is also of great significance. Particularly, what the Holy Spirit did as recorded in the book of Acts. It's actually a shame that so few Christians have even read the Bible, let alone understand it. And while I'm not claiming to have a perfect understanding of Scripture, I understand enough to know that the spirits claiming to be the Holy Spirit, are actually from the enemy!
Let me give you an example. Paul's conversion. What does Acts say happened to Paul during his conversion? Acts 9:1-9 reveals that Paul fell to the ground! The Bible does not reveal if it was the Holy Spirit that did this, but for the sake of the argument, let's say that it was (though I don't believe it was). Notice that Paul was receiving correction from Yeshua when this happened. If we take a look at instances in the book of Acts, instances where Yahweh isn't correcting anyone, we see that not one of them ever fell to the ground. The only ones who fell to the ground were the ones receiving correction! Think about that! And also think about how those who allegedly have the Holy Spirit fall in such a manner that there is a very serious risk of injury. Funny how the alleged proof that the Holy Spirit is doing those things can result in injury instead of healing, which is often what is promised.
When these counterfeit spirits aren't making an awe-inspiring display that fools the people into believing that they are the Holy Spirit, there's saying things which contradict what Yahweh revealed through his Law, the Prophets, and his son, Yeshua. And they also contradict the accounts that the historical records give concerning the Holy Spirit's actions. Records that Yahweh made sure were written by people of integrity! These spirits are calling Yahweh a liar! Among the lies that these spirits teach are vein repetition and counterfeit tongues (which numbs the brain, making them more susceptible to possession), that those who have the Holy Spirit can lose control over their bodies (that's actually demon possession), and prosperity gospel.
Of course, we can't forget the most basic test:
1 Beloved, do not believe every spirit, but test the spirits, whether they are of God; because many false prophets have gone out into the world. 2 By this you know the Spirit of God: Every spirit that confesses that Jesus Christ has come in the flesh is of God, 3 and every spirit that does not confess that Jesus Christ has come in the flesh is not of God. And this is the spirit of the Antichrist, which you have heard was coming, and is now already in the world. [1 John 1:3; NKJV]
Nobody seems to test the spirit concerning this one basic thing, or other like it (eg: whether Yeshua is the son of Yahweh, or is the Messiah). It's kind of important to get this information from the beginning, so that nobody will be deceived later on.