in God we trust

you can read the history of this motto, which first appeared on U.S. coins and bills in 1864, at the Department of the Treasury website (treas.gov). It's had its ups and downs (President Theodore Roosevelt, for example, took it off, expressing his "very firm conviction" that putting such a motto on coins was not a good idea). The Founders, who worked so very hard to establish the separation of church and state, would have agreed.