It is hard to deny that on matters of truth and love there is often significant confusion in evangelicalism. But, as Calvin put it, a pastor is given two voices, one for gathering the sheep and one for driving away wolves.
The following quotation from Dr Martyn Lloyd-Jones is both measured and convicting. It strikes the right tone for the necessity and nature of polemics.
"Do you agree with those who say that a spirit of love is incompatible with the negative and critical denunciation of blatant error, and that we must always be positive?
The simple answer to such an attitude is that the Lord Jesus Christ denounced evil and denounced false teachers...he denounced them as 'ravenous wolves' and 'whited sepulchres', and as 'blind guides.'...that is the language of the Scriptures.
It is not pleasant to be negative; it is not enjoyable to have to denounce and to expose error. But any pastor who feels in a little measure, and with humility, the responsibility which the Apostle Paul knew in an infinitely greater degree for the souls and well-being spiritually of his people is compelled to utter these warnings. It is not liked and appreciated in this modern flabby generation."
Martyn Lloyd-Jones, "Biblical Intolerance", Banner of Truth 371-2, p. 55