Well, perhaps some of the people are who are anti-religion have good empirical or theoretical reasons why they think the way they do. Perhaps whether people are pro- anti- or neutral towards religion they have reasons that support their position. I realise that you say that the people you meet don't, but the many atheists I know do. And anyway, being anti-religion does not entail a position on whether one believes in the supernatural.
And both positions are not belief systems. I'm quite surprised you are even saying that. It is something that I see religious people do in order to make their view appear to be similar to the views commonly held by atheists (presumably in an attempt to equalise things), but it is incorrect. Atheism is the rejection of belief in gods. It means that I, as an atheist, do not accept the view of deists. It does not mean that I BELIEVE that there are no gods, as in, this is something that I hold to be true, come what may. It means that my evaluation of the proposal that gods exist is that there is no extant evidence to support that belief. Should evidence otherwise come to light, then I would of course reevaluate my position and bring it into line with any new knowledge.