The United States Congress has legislated that the phrase "In God we trust" is the official motto of nation. After voting this into law, it has been re-approved every year, by both Democrats and Republicans. It has appeared on coins and paper money for over a century.
From time to time, various political groups - communists, libertarians, left-wingers, and atheists - have challenged the propriety of the motto, either in the press, or in court. Notice that atheists are here categorized as a political group: in such a circumstance, it is not philosophy which motivates, but public affairs.
Jews, Muslims, Christians, and others have been content with the motto because it is sufficiently generic.
Perhaps a more interesting challenge to the motto came, not from an atheist, but rather from religious Christian who happened also to be the President of the United States. Theodore Roosevelt had long felt that placing God's name on a coin was actually disrespectful to Him, and for two reasons: first, because a coin is the object of greed and materialism; second, because it had led to a number of jokes about politics, money, and banks.
Roosevelt, who had given several speeches urging the American public to read the Bible regularly, saw his opportunity in 1907, when a new coin was being designed. He directed the mint's artist to omit the motto, which had been on coins for over fifty years by that time. Public sentiment, the Congress, and eventually the Supreme Court would uphold the motto, which remains the official expression of the government to this day.