Don't publish comments from, or debate with, the dishonest (and where somebody is dishonest is a thing you will need to judge for yourself).
The dishonest have an agenda, a reason for commenting - and they are using your blog to propagate it.
What is the point of a traditional Christian blog publishing comments that seeks to undermine and subvert its blog posts? What is the point of overwhelming the Christian blog posts with following comments that are anti-Christian - and pro some secular agenda that is nearly always secular Left, nearly always pro-sexual revolution?
That would be taking one step forward and two steps back.
You may believe that you are publishing comments to refute them - but that may not be how the exchange appears.
When a commenter is dishonest, and when his aim is destructive, he has a massive advantage in debate - He can raise problems and doubts more simply and easily than they can be dealt-with; he can ask questions faster than you can answer them (a short and easily-understood question often needs a long and involved answer that is difficult to follow and needs concentration to follow - hence your answer will - often - not be followed).
When a commenter is parroting mainstream mass media opinion, he also has the advantage that his view is backed-up by what people (usually unconsciously) regard as 'evidence' (i.e. 1001 things they have heard, seen or read, somewhere - they aren't sure where - and sort-of accept as presumably valid).
A dishonest and subversive commenter can destroy certainty, belief and hope much more readily than you can patch-them-up.
Don't give them space and airplay, don't give them attention, don't waste your time on them. It will do more harm than good.