Beginning in the second chapter of the first book of St. Ambrose’s On the Holy Spirit, the bishop of Milan begins to use language that might strike the modern reader as harsh.
. . . to the impious it does not seem so.
For the heretics are wont to say . . .
How utterly confused is a course of argument which does not hold to the truth, and is involved in an inverted order of statements . . .
. . . if he persists in his perverse interpretation . . .
In our age, dominated by political correctness as it is, these phrases appear to be inappropriate and even hateful. In modern American parlance, if you have to insult your opponent, you have already lost the argument. Therefore, it is easy to dismiss St. Ambrose and other Fathers of the Church who are engaged in Apologetics. Ironically (thus far, at any rate), Ambrose is actually quite polite in comparison to some of the other Fathers (St. Athanasius comes to mind).
Judging them this way, however, is anachronistic — it unfairly places our own context over and above the context within which these words were written. Rhetoric was widely studied in the ancient world — indeed, it was very popular for rhetoricians to display their skill in public debates. Such name calling was par for the course (if not a tad bit tame, in this particular case).
Besides which, St.Ambrose is being quite truthful in his language. Those who do not accept the Holy Spirit as God are heretics and impious and whose arguments are perverse and confused. Note Matthew 12:32 and what Christ says of the Holy Spirit:
He who shall blaspheme against the Son of Man it shall be forgiven him, but he who shall blaspheme against the Holy Spirit shall never be forgiven, either here or hereafter.
Finally, St. Ambrose is following a rhetorical style used by Christ Himself. Note how, in Matthew 23:13 our Lord, God and Savior addresses the Pharisees:
But woe unto you, scribes and Pharisees, hypocrites! for you shut up the kingdom of heaven against men: for you neither go in yourselves, neither allow you them that are entering to go in.
Therefore, especially when reading the apologetic writings of the Fathers, it is important to understand the polemical language as normative so that it does not impede our ability to understand the argument that always follows.