This weekend on the Mall in Washington, a bunch of atheists — tens of thousands, including me -- will get together just to be counted as not having a personal god. Why? Whether the pollsters bemoan it or celebrate it, the percentage of Americans who are losing their religion is rising. And in a presidential election year, candidates need to take note. Two of those remaining, Donald Trump and Hillary Clinton, still give lip service to being religious -- even if many on either side of religion don't believe them or want to claim them. (Why would this be the...