There appear to be several different ways we may look at these verses, any one of which, or even a combination would shed light on this question for us:
1 There does not appear to be any one particular sin in view, otherwise Christ would have revealed it, lest his hearers even unintentionally commit it. So, whether you strangle your mother-in-law, or even kick Ted Jaracz in the nuts even if he deserves it, is not the issue. It is more a state of the mind, or more appropriately, the state of the heart that is important.
2 If you are concerned about it, you have'nt commited it.
3 The sin is against the Holy Spirit. It is not a sin against you or me, or even the "manifest operation of the spirit as revealed in WT literature" It is against the Holy Spirit. He decides what that sin is. He condemns, and an eternal condemnation it is. It is not for us, or even for those pompous degenerates who arrogantly claim divine sanction, while luxuriating in comfortable surroundings in WT HQ in New York, to dictate what this sin is.
4 The sin against the Holy Spirit is spoken of as being in two eras. Evidently one can commit this unforgivable sin in "This Age" and in "The Age to come" "This age" would be the time in which Jesus was alive, the "Jewish Age" and the "Age to come" would be the coming "Millennium Age" The one common factor in these two ages is the physical reality of the Presence of The Son of Man. Back in Christ's time the Pharisees actually saw the real Christ and saw the work of the Holy Spirit through His miracles. Rejecting Him, they rejected the Spirit. That was what bordered on the Ungforgivable. The text does not say whether or not they actually did commit this sin, but they were in danger of that very thing. Similarly, those in the Millennium will see the living Christ who will bring about even grander wonders by that same Spirit. Believe it or not there will be some who simply will not recognize this, ascribing these to the devil.
5 The age we live in now, the Gospel Age, brings the redeeming work of Christ's blood to all. There is no sin, and no person or group of persons that is beyond the infinite value of the blood of Christ
6 This is not to say that we need to be unrepentant now. The Unforgivable Sin may be a sin awaiting a future generation, but as far as we are concerned, the Bible does warn about an unrepentant heart. We can die in our sins, ie without "believing that Jesus is who He claimed to be". This is not the Unforgivable sin, but yet we die in a state of unforgiveness.[Jo 8:24] We will then reap the consequences of unforgiveness. You get one shot at eternal life, and it is now.
7 Those making a practice of sin show that they are not of that sort who have believed the claims of Christ, for, as John says, those who are born of Him practice righteousness. They may indeed sin, but they practice righteousness [1Jo 2:29]
Cheers