Nicene and Post-Nicene Fathers, Vol. IV:
Writings in Connection with the Donatist Controversy.: Chapter 62

Chapter 62.—139.  Petilianus said:  "And again it is written, ‘Every sin which a man shall sin is without the body; but he that sinneth in the Holy Spirit, it shall not be forgiven him, neither in this world, neither in the world to come.’"

140.  Augustin answered:  This too is not written as you have quoted it, and see how far it has led you astray.  The apostle, writing to the Corinthians, says, "Every sin that a man doeth is without the body; but he that committeth fornication sinneth against his own body." 2156   But this is one thing, and that is another which the Lord said in the gospel:  "All manner of sin and blasphemy shall be forgiven unto men:  but whosoever speaketh against the Holy Ghost, it shall not be forgiven him, neither in this world, neither in the world to come." 2157   But you have begun a sentence from the writing of the apostle, and ended it as though it were one from the gospel, which I fancy you have done not with any intention to deceive, but through mistake; for neither passage has any bearing on the matter in hand.  And why you have said this, and in what sense you have said it, I am wholly unable to perceive, unless it be that, whereas you had said above that all were condemned by the Lord who had broken any one of His commandments, you have considered since how many there are in your party who break not one but many of them; and lest an objection should be brought against you on that score, you have sought, by way of surpassing the difficulty, to bring in a distinction of sins, whereby it might be seen that it is one thing to break a commandment in respect of which pardon may easily be obtained, another thing to sin against the Holy Ghost, which shall receive no forgiveness, either in this world or in the world to come.  In your dread, therefore, of infection from sin, you were unwilling to pass this over in silence; and again, in your dread of a question too deep for your powers, you wish to touch cursorily on it in passing, in such a state of agitation, that, just as men who are setting about a task in haste, and consequent confusion, are wont to fasten their dress or shoes awry, so you have not thought fit either to see what belongs to what, or in what context or what sense the passage which you quote occurs.  But what is the nature of that sin which shall not be forgiven, either in this world or in the world to come, you are so far from knowing, that, though you believe that we are actually living in it, you yet promise us forgiveness of it through your baptism.  And yet how could this be possible, if the sin be of such a nature that it cannot be forgiven, either in this world or in the world to come?

Footnotes

1 Cor. vi. 18.

Matt. 12:31, 32.