You're missing the point. Atheists believe themselves superior because they have truth on their side; and Christians believe themselves superior because they have God and Jesus on their side. But it's all just trash talk until they meet on a level playing field: The marketplace of ideas.
Again: When an atheist and a Christian sit down at a table, you have exactly the same thing on either side of the table: an intellectual with a big ego and a certainty that he’s right. Neither side has the ability to prove themselves superior *before* meeting in the marketplace of ideas. Obviously neither side can prove that it is superior; they're all fallible human beings. It's only the marketplace of ideas that will eventually distinguish between the two.
Quit trying to exclude one of the parties before the contest even begins. Or, if you have to exclude someone because they've fallen short of expectations, then exclude the Christians; they're the ones that claim to have infallibility on their side. Christians are the ones falling short of their own high expectations. Athesists, on the other hand, never claimed to be anything more than fallible.
I think its a shame that your post started out so strong, the first two paragraphs couldnt really be faulted in my opinion but then in the final one you do exactly what you mentioned in the first.
Unless that was some sort of deliberate ploy, aiming for someone to point it out precisely as I did but I'm not sure that's what you were aiming to do.
Christians dont claim to be infallible, that's precisely the opposite of what any Christian would claim and it was heretical to claim otherwise, in most of the Christian traditions there is greater doubt about what can be known with certainty and about mankinds ability to know it than there is anything else, this was a bountiful (and unacknowledge today) heritage for scientists like Francis Bacon when they developed their investigative techniques.
However, it has been one of the extremely unfortunate legacies of evangelism that it promises to people certainty, using it as an enticement, or perhaps preys upon the needs and anxieties of some people for certainty. There is much that is in evangelism which resembles marketing tricks, I would say early as well as later but I would say most definitely in the case of later day evangelism, especially with Tele-evangelism and the rise of evangelism as a cultural phenomenon of importance back during the Carter administration in the US (a lot of the younger posters probably dont remember the significance of testifying repeatedly to being a born again christian was at that time, about as often as Kennedy had to say he wouldnt be serving two masters if he was elected).
The problem being that as having developed often in response to or in a very close relationship to evangelism militant atheism mirrors it. Consider the clip that Peguy posted of Richard Dawkins speaking to the RC priest, he had a preprepared script which would have fit the framework of a militant creationist, solo scriptural southern baptist but when located in an entirely different context it made no sense what so ever.
There are big egos involved and more often than not it is played out as a contest and competition, truth and God are just easy casualties, the important thing is a sort of satisfaction which comes with the feeling of winning or defeating the other. As to why that is and as to why the internet seems to have stoked it SO much is another topic and probably an interesting one, it probably speaks in no short measure to what or how people ascribe value or worth to themselves and others in the present day, its all about the appearences of being smart and clever I think, in a terrible school yard way.
Any social or political "harm" has been neutralised perfectly by the fact that the energy is channelled into metaphysical speculation, while both sides may occasionally seek to anchor it all in some reflection on the consequences of belief in terms of actions that's minor, I really think it is, and only used ever to illustrate the villainy of the opposition. Imagine if the same energy and motivation was directed to democratising participation in elections, workplaces, schools, health provision? Nope, discussing God and an afterlife is a pretty useful diversion from discussing tradition, innovation, economy, life etc.