Translation
but whoever might dare to blaspheme against the Holy Spirit does not have forgiveness to the age, rather he is held liable for a sin that lasts for an entire age.
Paraphrase
However, the kind of person that refuses to acknowledge the obvious work of the Holy Spirit will never be able to find forgiveness, never! That type of person will always be held guilty for their actions.
TYPE OF SIN OR TYPE OF PERSON?
Here the emphasis is on the type of person. If you are a person whose life is characterized by sin and you do not change the kind of person you are, you will be punished. However, if you change and start following God’s instructions, you will be forgiven. But some people find it harder than others to turn their lives around. If you are the type of person that chooses to ignore the obvious work of the Holy Spirit or attributes it to another source of power, and you do so for your own personal gain, it is quite likely that you will never be able to change the type of person you are. You will have invested so much of yourself in this position that you are not likely to be willing to walk away from it. Without changing the course of your life, the consequences of your choices will follow you forever.
It is not God’s willingness to forgive that is limited, rather it is human nature that is limited in its willingness to change.
This was a rebuke against the Pharisees who claimed earlier in this passage that the miracles of Jesus (obvious demonstrations of the power of the Holy Spirit) were done by the power of Beelzebub, the leader of all the demons. Because of the position the Pharisees had taken and as long as they held that position, they could not be forgiven, and because they wanted to keep the reputation they had built it was unlikely that they would ever change the type of person they were.