D. A. Carson argues that polemical theology is biblical but can also be dangerous:
. . . any robust theology that wounds and heals, that bites and edifies and clarifies, is implicitly or explicitly engaging with alternative stances.
In a world of finite human beings who are absorbed in themselves and characterized by rebellion against God, polemical theology is an unavoidable component of any serious theological stance, as the Bible itself makes clear.
But then he points to the dangers:
Nevertheless there is something wrong-headed about making polemical theology the focus of one’s theological identity.
This can be done in many ways.
There are well-known scholars whose every publication has an undertone of “everyone-has-got-this-wrong-before-me-but-here-is-the-true-synthesis.”
Some become far better known for what they are against than for the overflow of their worship or for their generosity to the needy or even for their affirmation of historically confessed truth.
Still other Christians develop websites and ministries whose sole aim is to confute error. God knows there is plenty of error to confute. To make the refutation of error into a specialized “ministry,” however, is likely to diminish the joyful affirmation of truth and make every affirmation of truth sound angry, supercilious, self-righteous—in a word, polemical.
In short, while polemical theology is just about unavoidable in theory and should not, as a matter of faithfulness, be skirted, one worries about those who make it their specialism.
Carson also makes the point that “polemical theology ought to develop a wide range of ‘tones’”:
Within the space of six short chapters, Paul can be indignant with his readers, but he can also plead with them. He openly admits he wishes he could be present with them so he could better judge how he should adjust his tone. He can be scathing with respect to his opponents, precisely because he wants to protect his readers; he can devote several paragraphs to clarifying and defending his own credibility, not least in demonstrating that his core gospel is shared by the other apostles, even though he insists he is not dependent on them for getting it right. He happily connects his theological understanding to ethical conduct.
All of this suggests that a mature grasp of the potential of polemical theology wants to win and protect people, not merely win arguments.
You can read the whole thing.