In Part I of this redux of Tom Wells excellent essay On The Ethics of Controversy (PDF), I covered what attitudes we *should* take in debating truth.  However, he also mentions the many erroneous conclusions we should NOT draw based on the aforementioned principles of civil discourse.

1. We must not conclude that in order to be ethical in conducting
controversy we have to recognize men as Christians when they fail the
biblical tests of Christianity.

At some point one must face the fact that the kinds of disavowals and denials one finds in many branches of classic liberalism, and repeated by the major proponents of religious pluralism, are  much deeper even than the chasms between, say, Russian  Orthodoxy and American Pentecostalism, or between Roman Catholicism and classic evangelicalism; we are dealing with  “different religions,” in the strongest sense of that expression. (J.  Gresham Machen)

In other words, it is not uncharitable to declare that someone who holds beliefs markedly unbiblical is just not a Christian.  While we should not judge them unchristian for not believing exactly as we do, there is a reasonable and logical point where we must honestly conclude that a person may call themselves Christian, but their theology is clearly unbiblical or so poorly reasoned as to be beyond intellectual honesty, and therefore, unchristian.

2. We must not conclude that it is wrong to press the points on which we feel confident.

By the way some people react, you’d think that any amount of theological or moral certainty was hubris.  But such a position is practically and logically untenable.

To adopt this position would be to paralyze all discussion. It  would stop us from loving others and seeking their good by  correcting them where they need correction. And incidentally,  but viciously, if others adopted the same position toward us we would lose the help their criticism offers….

On the contrary we must contend for what we hold to be truth.

[T]o proceed with a healthy doubt about one’s own moral rightness only means treating one’s opponents with respect and granting the possibility of error. It  does not mean refraining from action. The legal scholar Michael Perry, himself a Roman Catholic, has put the point nicely: “Although we must resist infallibilism … at any given moment our convictions  are what they are.” If we do not act on such convictions, how will truth make its way in this world?

3. We must not conclude that it is wrong to vigorously denounce critical error.

The example of our Lord Jesus and the apostles shows this plainly. Though they spoke by inspiration and we do not, yet passionate regard for truth will move us to speak and write with a zeal commensurate with the importance of the error with which we are dealing after we have exhausted all avenues that might show that we have misunderstood what has been said. We must never forget: some errors are damning.

4. Given the importance of controversy we must not avoid it out of cowardice.

No one likes to lose friends or be scorned unnecessarily, but there is only one person who commands our absolute allegiance: God, as He has revealed Himself in His written and personal Word. Faithfulness to Him has always occasioned controversy and it always will.

5. Controversy is to be done as gently and compassionately as is consistent with zeal for the truth.

There are good and bad ways of fulfilling the ministry of criticism
among Christians. This ministry is important, for all who seek truth and wisdom take up from time to time with wrong ideas and need correction. But discussion and debate ordinarily achieve more than gestures of denunciation. To think of sustained denunciation as the essence of faithful witness … is very wrong. Denouncing error has its place, but since it easily appears  arrogant and generates much unfruitful unhappiness, anyone who feels drawn to it should take a lot of advice before yielding to the urge. (J.I. Packer)

CONCLUSION

To sum it up with an anonymous poem:

Controversy in religion is a hateful thing.
It is hard enough to fight the devil,
the world, and the flesh,
without private differences in our own camp –
But there is one thing
which is even worse than controversy,
and that is false doctrine tolerated,
allowed, and permitted without
protest or molestation …
Three things there are which men
never ought to trifle with:
a little poison,
a little false doctrine,
and a little sin.