From the New Republic Online
Pledge Class
There's no reason that the pledge must include an explicit reference to God. In fact, before 1954, it didn't. Schoolchildren simply pledged their allegiance to "one nation, indivisible, with liberty and justice for all." Congress added the reference to God in 1954 to distinguish the United States from the "godless" Soviet Union. This is precisely the kind of state endorsement of religion that the First Amendment was designed to prohibit. Critics of the decision keep talking about the religious faith of the founders, but the fact is that this country was founded in large part by religious dissenters. Our Bill of Rights was written against a backdrop of centuries of efforts by the British government to control religious beliefs.