I'm not offended at magicmiles's statement either. He's saying what he honestly believes, and that's important, because it means he respects the people here enough to say what he thinks even though he knew going in that it wouldn't be received well. That it probably would be an offensive statement to a number of people. If he wasn't willing to be honest (even though he's almost certainly wrong about it, which is not the same as him knowingly lying) when it was unpopular, how could we ever trust him to be honest in other circumstances?
That being said, I do think he's wrong in that belief. For starters, he's advanced the proposition that every member of this forum has some belief in his god, even if it's buried really deeply. But he has no way to realistically verify that statement - no way to actually test whether someone has a secret, hidden, or buried belief in his god. Furthermore, his proposition can only be true in one instance - if every member of this forum actually does have that buried belief in his god. In every other instance, it would necessarily be false, and thus falsify his proposition.
Given that it's his proposition, he needs to be able to demonstrate a way to verify its truth value. If he can't, then it's not a useful belief. It would be like advancing a belief in a specific race of aliens who lived on a specific planet - while he could try to convince anyone he wanted that it was true, without evidence to support it, there's no reason to accept it as true.