It's not. Go read the passage. It's not concerning salvation, but whose power Jesus does His works by.
so forgiveness is not about salvation??
they attributed the works to satan because they did not believe he was from God. so who else could it be from?
Unbelief is the root cause..and the unforgivable sin
he who believes, he who does not believe,, there is what separates a child of God and a non child of God..