Having missed the chance to reply in a thread with similar topic to this, I'll follow Golden Eagle's advice and open another new.
Have you ever noticed the way Paul brings up things in his letters?
Sometimes referred as the sandwich model, it begins by telling the other participant(s) about the good things we perceive in them or their views. If there's much we don't agree on, if anything at all, I guess it would not cost us too much to express our gratitude or respect towards them as persons with a few words or so. It does not or should not need to be false pretending. As God's children, this should not be too much asked, but such spontaneous love should already reside within us. It's only a matter of letting it flow. I personally find this aspect very important when it has to do with debating with people who don't yet know Jesus. Because Jesus commanded us to love as He did. I am not talking of extremes, but a kind comment etc.
But, in Paul's approach, he does not spare his words either when it comes to correcting someone's behavior and things like that. I believe many Christians actually perhaps unconsciously imitate his style as for this, whilst forgetting about the first part mentioned above. Yet I think more or less contextual preaching is always a good option, though it does not or at least should not undermine the truth of God's Word.
Lastly, Paul forecloses often with a smoother ending, giving the participant(s) a chance to reflect upon what was said.
I am not condemning anyone for how they choose to participate here, or otherwise either, but I have come to experience this has often proven itself quite a fruitful way of approaching people. And it's not about being false, but coming forward with an attitude that keeps the debates on a positive tone even with disagreements. There have been a number of times I've been provoked to get irritated, but why should someone's perceptions or opinions affect my life?
Just thought to share this, I can testify for its effectiveness.