Tim Keller has a very good series of articles on Gospel Polemics. In the first article he discusses a historical exchange between Martin Lloyd-Jones and T. T. Shields, and quotes Lloyd-Jones as saying, “Polemics is medicine, not food.”
1. Carson’s Rule—You don’t have to follow Matthew 18 before publishing polemics.
2. Murray’s Rule—You must take full responsibility for even unwitting misrepresentation of someone’s views.
3. Alexander’s Rule—Never attribute an opinion to your opponent that he himself does not own.
4. Gillespie’s Rule A – Take your opponents’ views in total, not selectively.
5. Gillespie’s Rule B – Represent and engage your opponents’ position in its very strongest form, not in a weak ‘straw man’ form.
6. Calvin’s Rule – Seek to persuade, not antagonize, but watch your motives!