This would be great...both groups would have to agree on just what this is. Hopefully the ideal common ground doesn't become a war zone. I think that atheists (particularly the hostile ones) would do well to accept religion as being more natural to man than irreligion.
I think that Christians (particularly the... well, just most of them) would do well to accept that irreligion is just as "natural" as religion, and not per se evil, depraved, reprobate, sinful, disgusting, rebellious, criminal, immoral... you get my point?
But I have a few other problems with your approach.
I agree with GMS' argument from the video that religion is not a "mental illness". It is not a "psychological abnormality", like Philo called in in the thread title. It is "natural". It is "normal".
But I think that is, for the most part, and especially for apologetic discussions, a completely irrelevant argument.
Something being "natural" doesn't say anything else about it. It just explains the origin.
By now, we should know that "natural" does not mean "good" or even "preferable". It's a fallacious argument to equate these.
And by far does "natural" not mean "correct" or "truthful".
So even if religion and religious thought is "normal" and "natural"... should me follow it? Should we promote it? And, what kind of "religion"?
Somehow, everyone seems to come to the, erm, "natural" reaction of: "Why, mine, of course!"
Atheists should not use the argument of "Religion is a mental illness".
But in the same way, theists should not use the argument of "Religion is natural and normal".