Fence-sitting has its purpose when we ant to develop a good understanding before we take a position. Agnostics believe that they sit on the fence so they can evaluate the pros and cons of religiosity and atheism. The problem with this is that agnostics (most of them I would hope) would not call themselves agnostic with respect to flat-earth and globe. Why do they this with regards to God? Atheists say there is no god because there is absolutely no evidence for it, so it doesn't make sense to sit on the fence of something that has zero evidence for it. You might as well be agnostic about pastafarianism and the flying teapot. Agnosticism makes sense, but when evidence is overwhelming, then we should use our energy to move and not keep sitting on that fence.