I think atheists are capable of acting like a superstitious cult like the best of us, but if they want to try this, good luck to them!
Oh wait, they don't believe in that either (most of them anyway, not to generalize).
Nothing happens to me either way if such a motto appears on a building or coin, or doesn't, so I don't really have a stake. I think the main reason people are interested in stuff like this is the legal precedents that can affect long term trends, etc.
Don't forget, ALL costs could be used to feed hungry children or spent on something else, and that goes for any cause! One can always argue there is something "more important." Just sayin'!