ANSWER: "but anyone who blasphemes the Holy Spirit will never be forgiven. This is a sin with eternal consequences." Mark 3:29.
IMPLICATION: The above text are words of Christ on this subject, showing that there are "Unpardonable sins", which are sins against the Holy Spirit. Sometime ago i asked a priest "Does this mean that God REFUSES to forgive this sin" ?
The priest could not give a satisfactory conclusive reply, until one day after years of research and prayer, i stumbled upon an explanation.
HERE IS WHAT I LEARNT: God does not REFUSE forgiveness. Rather, when one sins against the Spirit of God, he CASTS GOD OUT of himself and SHUTS THE HEART TO HIS LIGHT. So that such a person is UNABLE TO ASK for mercy anymore. The "Unpardonable" does not mean God changes from "Forgiving Father" to an "Unforgiving Judge", so that he turns his face from someone weeping and begging for mercy, NO !!!. He is Always FORGIVING. Even those who are in Hell cannot ask for pardon, that is why they cannot be forgiven.
The GRACE of remorse/contrition is very expensive gift of the Holy Spirit, given unto the sincerely repentant ones. I tell you, there are many Catholics today who have shut their hearts to God's grace by continuous abuse of Sacraments for instance and other sins; they personally kill the voice of their consciences by refusing God's light/call to repentance so many times, that those sins become "Normal" and even "A way of life" to them.
For this grace is meant to rise our sensitivity to sin and make us weep for our sins, but for someone who is dead in sin, he cannot possibly weep or feel really sorry for his sin. He may even boast about his sins to his friends and feel like a "big Shot".
This is what it means to commit an "Unpardonable" sin. Whenever such a sinner opens his heart to God's light, he sees his sorry state, and confesses with all his heart, God Forgives him for sure, for he promised "Even if your sins be as red as scarlet, i shall make you as white as wool".
God bless you all. I hope we understood this one.