An unbiblical doctrine can't be ignored just because the critic fails to fulfill the directives of Matthew 18. Retaining the Standard There is no reason to threaten our unity by frivolous debate. However, many debates are not frivolous, but are worthy of our best efforts. This kind of protection of the truth is not a passive enterprise. It's active and energetic.
Arguments are good and dispute is healthy.
They clarify the truth and protect us from error and religious despotism. When the church discourages principled debates and a free flow of ideas it leads to shallow Christianity and a false sense unity. No one gets any practice learning how to field contrary views in a gracious and productive way. The oneness they share is contrived, not genuine. And they lose the ability to separate the wheat from the chaff.