The ignorance of man - Audio Talk
1 Timothy 1:13 
John Calvin's commentary of 1 Timothy 1:13
(Paul) Who was formerly a blasphemer and persecutor; a blasphemer against God, a persecutor and oppressor against the Church. We see how candidly he acknowledges that it might be brought against him as a reproach, and how far he is from extenuating his sins, and how, by willingly acknowledging his unworthiness, he magnifies the greatness of the grace of God. Not satisfied with having called himself a "persecutor," he intended to express more fully his rage and cruelty by an additional terns, an oppressor.
Because I did it ignorantly in unbelief "I obtained pardon," said he, "for my unbelief; because it proceeded from ignorance;" for persecution and oppression were nothing else than the fruits of unbelief.
But he appears to insinuate that there is no room for pardon, unless when ignorance can be pleaded in excuse. What then? Will God never pardon any one who has sinned knowingly? I reply, we must observe the word unbelief; [20] for this term limits Paul's statement to the first table of the law. Transgressions of the second table, although they are voluntary, are forgiven; but he who knowingly and willingly breaks the first table sins against the Holy Spirit, because he is in direct opposition to God. He does not err through weakness, but, by rushing wickedly against God, gives a sure proof of his reprobation.
And hence may be obtained a definition of the sin against the Holy Ghost; first, that it is open rebellion against God in the transgression of the first table; secondly, that it is a malicious rejection of the truth; for, when the truth of God is not rejected through deliberate malice, the Holy Spirit is not resisted. Lastly, unbelief is here employed as a general term; and malicious design, which is contrasted with ignorance, may be regarded as the point of difference. [21]
Accordingly, they are mistaken who make the sin against the Holy Ghost to consist in the transgression of the second table; and they are also mistaken, who pronounce blind and thoughtless violence to be a crime so heinous. For men commit the sin against the Holy Spirit, when they undertake a voluntary war against God in order to extinguish that light of the Spirit which has been offered to them. This is shocking wickedness and monstrous hardihood. Nor is there room for doubting that, by an implied threatening, he intended to terrify all who had been once enlightened, not to stumble against truth which they knew; because such a fall is destructive and fatal; for if, on account of ignorance, God forgave Paul his blasphemies, they who knowingly and intentionally blaspheme ought not to expect any pardon.
But it may be thought that what he now says is to no purpose; for unbelief, which is always blind, can never be unaccompanied by ignorance. I reply, among unbelievers some are so blind that they are deceived by a false imagination of the truth; and in others, while they are blinded, yet malice prevails. Paul was not altogether free from a wicked disposition; but he was hurried along by the thoughtless zeal, so as to think that what he did was right. Thus he was an adversary of Christ, not from deliberate intention, but through mistake and ignorance. The Pharisees, who through a bad conscience slandered Christ, were not entirely free from mistake and ignorance; but they were instigated by ambition, and base hatred of sound doctrine, and even by furious rebellion against God, so that maliciously and intentionally, and not in ignorance, they set themselves in opposition to Christ. [22]
Footnotes:
[20] "Through unbelief, or not having faith."
[21] -- "In the definition of the sin against the Holy Spirit, Unbelief is the general term, and malicious intention, which is the opposite of ignorance, may be regarded as that which logicians call the difference, which limits what was general."
[22] "It may deserve consideration whether a large portion of this able argument might not have been avoided, by means of a different collocation of the passage. "Who was formerly a blasphemer, and a persecutor, and an oppressor, (for I did it ignorantly in unbelief,) but I obtained mercy, and the grace of our Lord was exceedingly abundant, with faith and love which is in Christ Jesus." -- Ed.
If you would like to know more about John Calvin here are three excellent talks which introduce Him - Editor