Religious people are less intelligent than atheists

[Mister Agenda]

Let me ask this because these kinds of threads pop-up often enough. Why is it so important for atheists to prove they are more intelligent/rational than theists?

It isn't important, and an average IQ difference, especially if small, says very little about whether a given atheist is smarter than a given theist. It would be completely illogical to say 'atheists average 2 points higher on IQ tests, I'm an atheist and you're a theist, therefore I must have a higher IQ than you'.

If the finding were reversed, it would still be an interesting topic.