Interesting read. The key being whether a sinner is willful (defiant) or unwitting.
Jesus was responding to those who accused Him of performing miracles not by the power of the Holy Spirit, but from Satan.
Mark 3:22 And the scribes who came down from Jerusalem said, "He has Beelzebuub," and,"By the ruler of the demons He casts out demons."
I don't believe a Christian will ever question by who's power Jesus performed miracles, so the unpardonable sin would not be something they could commit. However, is it possible that Jesus is also referring to a later time where people curse the Holy Spirit for not revealing to them the truth of who Jesus Christ is?
Mark 3: 29 "but he who blasphemes against the Holy Spirit never has forgiveness, but is subject to eternal condemnation"-
17 All unrighteousness is sin, and there is sin not leading to death. 18 We know that whoever is born of God does not sin; but he who has been born of God keeps himself,[e] and the wicked one does not touch him. 19 We know that we are of God, and the whole world lies under the sway of the wicked one. 20 And we know that the Son of God has come and has given us an understanding, that we may know Him who is true; and we are in Him who is true, in His Son Jesus Christ. This is the true God and eternal life. 21 Little children, keep yourselves from idols. Amen. 16 If anyone sees his brother sinning a sin which does not lead to death, he will ask, and He will give him life for those who commit sin not leading to death. There is sin leading to death. I do not say that he should pray about that.
It seems Paul is saying not to pray for those who commit the sin unto death since they are lost and have not been given an understanding of God. We pray for believers and all those who will eventually be brought to Him.