 I've done something either so bad that God can never forgive me. Well, of course, you're never going to ask him to forgive you if you think that. So that's the only reason why it's the unforgivable sin, the sin against the Holy Spirit. But in the age of the rabbis before Christ, they thought of something else. They thought that breaking of this commandment is the unforgivable sin, taking God's name in vain.