The Unpardonable Sin
When the unpardonable sin comes up in scripture it is when the Jews accused Jesus of working with devils when he did his miracles.
But I don't believe that we can commit it today. Let me show you some scripture where people mocked the miraculous workings of the Holy Spirit, and how they got saved.
Acts 2:4-15 And they were all filled with the Holy Ghost, and began to speak with other tongues, as the Spirit gave them utterance. (5) And there were dwelling at Jerusalem Jews, devout men, out of every nation under heaven. (6) Now when this was noised abroad, the multitude came together, and were confounded, because that every man heard them speak in his own language. (7) And they were all amazed and marvelled, saying one to another, Behold, are not all these which speak Galilaeans? (8) And how hear we every man in our own tongue, wherein we were born? (9) Parthians, and Medes, and Elamites, and the dwellers in Mesopotamia, and in Judaea, and Cappadocia, in Pontus, and Asia, (10) Phrygia, and Pamphylia, in Egypt, and in the parts of Libya about Cyrene, and strangers of Rome, Jews and proselytes, (11) Cretes and Arabians, we do hear them speak in our tongues the wonderful works of God. (12) And they were all amazed, and were in doubt, saying one to another, What meaneth this? (13) Others mocking said, These men are full of new wine. (14) But Peter, standing up with the eleven, lifted up his voice, and said unto them, Ye men of Judaea, and all ye that dwell at Jerusalem, be this known unto you, and hearken to my words: (15) For these are not drunken, as ye suppose, seeing it is but the third hour of the day.
So, the Holy Spirit was present there and people mocked what the Holy Spirit was doing. Did Peter stand up and declare that they had committed the unpardonable sin? No, Peter tells them to repent, and be baptized every one of you in the name of Jesus Christ for the remission of sins, and we read that about three thousand souls who listened to what Peter had to say and got saved and were baptized.
The logic is that if the mockers had committed the unforgivable sin then Peter wouldn't tell them to believe, repent and be baptized, and even if Peter was wrong to say that then why does it say that "they continued stedfastly in the apostles' doctrine and fellowship"?
The answer here is that they didn't commit the unpardonable sin, and it was only Jesus who spoke of this sin, and he did so to the Pharisees and Scribes who were accusing him with being in league with the devil in order to perform miracles.