I agree with nowwhat? Great point about Paul.
I think it was the old Aid book that said the "unforgivable sin" was, "denying an obvious manifestation of the holy spirit." The example used of the religious leaders bribing the soldiers assigned to guard Jesus tomb for them not to speak of Jesus resurrection even though those leaders knew what the soldiers had seen. Their interest was in preserving their position and denying Jesus. What else could be done to convince them? Therefore they were guilty of unforgivable sin.