I'm going to try to anticipate the response to the last post by some people who will say "your claim that using the phrase is illegal is dubious, and it's historical so its got to be okay."
I said that I thought that it was wrong for the government to print "In God We Trust" on currency, but I only went into detail about the legal issues. The psychology of "Us Versus Them" is what really concerns me. By establishing the 'we' (aka us), by default there will be a them. This is unnecessarily divisive. It served a purpose in the 1950's cold war red scare days, but even then it was just as illegal and wrong. I suppose it's no coincidence that atheists are the least trusted and least likely to get voted for minority group. There is an excuse for exclusion being promoted by the government on every piece of currency floating around.
This is part of the Blog Against Theocracy project.