ANSWER: This is too large a question for our single column. It is not a single, isolated, wicked act, but the culmination of a series of deliberate acts of known sin, the outcome of a willful rejection of light and a defiant resistance of the Holy Spirit's pleadings and warnings, till the capacity for repentance and saving faith has been destroyed. God does not close the door of salvation, but the impenitent man himself locks the door and throws away the key in his hatred of "recognized eternal holiness," saying, "evil be thou my good." A doctor finds a cure for the plague, a second physician prepares it, and a third applies it. While it would not necessarily be fatal to neglect or even offend the first two, it would be certain destruction to be plague-smitten to neglect the third persistently by refusing to take the medicine. This illustrates why sinning against the Holy Spirit is more dreadful than sinning against the Father or the Son.
— Steele's Answers pp. 25, 26.